path: root/inputmethod/fcitx5-mozc/patches/patch-2.26.4282.100

$NetBSD: patch-2.26.4282.100,v 1.1 2021/02/17 15:29:51 ryoon Exp $

* Update to 2.26.4282.100

diff --git android/gen_mozc_drawable.py android/gen_mozc_drawable.py
index 92e58828a..3b8fc46c1 100644
--- android/gen_mozc_drawable.py
+++ android/gen_mozc_drawable.py
@@ -353,7 +353,7 @@ def _ParseStyle(self, node, has_shadow, shader_map):
     stroke_map = {'style': 'stroke', 'shadow': has_shadow}
 
     # Special warning for font-size.
-    # Inkscape often unexpectedly converts from sytle to font-size attribute.
+    # Inkscape often unexpectedly converts from style to font-size attribute.
     if node.get('font-size', ''):
       logging.warning('font-size attribute is not supported.')
 
diff --git android/gen_touch_event_stats.py android/gen_touch_event_stats.py
index 2a28ba15d..f38f9b03a 100644
--- android/gen_touch_event_stats.py
+++ android/gen_touch_event_stats.py
@@ -112,7 +112,7 @@ def GetAverage(source_value, stats_type):
       return 0
     # Cumulative average values are multiplied by 10^7
     # when usage stats are sent to the log server.
-    # Here we get original value by dividing the avarage value.
+    # Here we get original value by dividing the average value.
     return cumulative_average / 1e7 / count
 
   # c.f. usage_stats/usage_stats_uploader.cc
diff --git base/BUILD base/BUILD
index 83f5740e4..6dca976f7 100644
--- base/BUILD
+++ base/BUILD
@@ -60,7 +60,6 @@ test_suite(
         ":config_file_stream_test_android",
         ":cpu_stats_test_android",
         ":encryptor_test_android",
-        ":flags_test_android",
         ":hash_test_android",
         ":iterator_adapter_test_android",
         ":logging_test_android",
@@ -101,7 +100,6 @@ cc_library_mozc(
         ":const",
         ":file_stream",
         ":file_util",
-        ":flags",
         ":mmap",
         ":mutex",
         ":number_util",
@@ -122,25 +120,10 @@ cc_library_mozc(
 
 cc_library_mozc(
     name = "flags",
-    srcs = ["flags.cc"],
     hdrs = ["flags.h"],
     deps = [
         ":port",
         "@com_google_absl//absl/flags:flag",
-    ] + select_mozc(
-        client = [":singleton"],
-        default = ["//base"],
-    ),
-)
-
-cc_test_mozc(
-    name = "flags_test",
-    size = "small",
-    srcs = ["flags_test.cc"],
-    requires_full_emulation = False,
-    deps = [
-        ":flags",
-        "//testing:gunit_main",
     ],
 )
 
@@ -150,16 +133,15 @@ cc_library_mozc(
     hdrs = ["init_mozc.h"],
     copts = ["-DMOZC_BUILDTOOL_BUILD"],
     visibility = ["//:__subpackages__"],
-    deps = select_mozc(
+    deps = [
+        "@com_google_absl//absl/flags:flag",
+    ] + select_mozc(
         client = [
             ":file_util",
-            ":flags",
             ":logging",
+            "@com_google_absl//absl/flags:parse",
         ],
-        default = [
-            "//base",
-            ":flags",
-        ],
+        default = ["//base"],
     ),
 )
 
@@ -168,17 +150,16 @@ cc_library_mozc(
     srcs = ["init_mozc.cc"],
     hdrs = ["init_mozc.h"],
     visibility = ["//:__subpackages__"],
-    deps = select_mozc(
+    deps = [
+        "@com_google_absl//absl/flags:flag",
+    ] + select_mozc(
         client = [
             ":file_util",
-            ":flags",
             ":logging",
             ":system_util",
+            "@com_google_absl//absl/flags:parse",
         ],
-        default = [
-            "//base",
-            ":flags",
-        ],
+        default = ["//base"],
     ),
 )
 
@@ -227,7 +208,6 @@ cc_library_mozc(
         client = [
             ":clock",
             ":const",
-            ":flags",
             ":mutex",
             ":singleton",
             "@com_google_absl//absl/strings",
@@ -236,7 +216,10 @@ cc_library_mozc(
             "//base",
             "//base:logging_extensions",
         ],
-    ) + [":port"],
+    ) + [
+        ":port",
+        "@com_google_absl//absl/flags:flag",
+    ],
 )
 
 cc_test_mozc(
@@ -576,10 +559,10 @@ cc_binary_mozc(
     deps = [
         ":double_array_def",
         ":file_stream",
-        ":flags",
         ":init_mozc_buildtool",
         ":logging",
         ":util",
+        "@com_google_absl//absl/flags:flag",
         "//third_party/darts/v0_32",
     ],
 )
@@ -733,10 +716,10 @@ cc_test_mozc(
     deps = [
         ":file_stream",
         ":file_util",
-        ":flags",
         ":mmap",
         ":util",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -800,11 +783,11 @@ cc_test_mozc(
     deps = [
         ":file_stream",
         ":file_util",
-        ":flags",
         ":logging",
         ":number_util",
         ":util",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -893,10 +876,10 @@ cc_binary_mozc(
     name = "process_main",
     srcs = ["process_main.cc"],
     deps = [
-        ":flags",
         ":init_mozc",
         ":logging",
         ":process",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -925,11 +908,11 @@ cc_test_mozc(
     deps = [
         "logging",
         ":file_util",
-        ":flags",
         ":process_mutex",
         ":system_util",
         ":util",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -956,9 +939,9 @@ cc_binary_mozc(
     name = "run_level_main",
     srcs = ["run_level_main.cc"],
     deps = [
-        ":flags",
         ":init_mozc",
         ":run_level",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -1016,9 +999,9 @@ cc_test_mozc(
     deps = [
         ":config_file_stream",
         ":file_util",
-        ":flags",
         ":system_util",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -1169,10 +1152,10 @@ cc_test_mozc(
     visibility = ["//visibility:private"],
     deps = [
         ":encryptor",
-        ":flags",
         ":system_util",
         ":util",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -1183,11 +1166,11 @@ cc_binary_mozc(
     deps = [
         ":encryptor",
         ":file_stream",
-        ":flags",
         ":init_mozc",
         ":logging",
         ":mmap",
         ":util",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
@@ -1198,10 +1181,10 @@ cc_binary_mozc(
     visibility = ["//visibility:private"],
     deps = [
         ":encryptor",
-        ":flags",
         ":init_mozc",
         ":logging",
         ":util",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -1288,11 +1271,11 @@ cc_binary_mozc(
     srcs = ["cpu_stats_main.cc"],
     deps = [
         ":cpu_stats",
-        ":flags",
         ":init_mozc",
         ":port",
         ":thread",
         ":util",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
@@ -1326,10 +1309,10 @@ cc_binary_mozc(
     name = "stopwatch_main",
     srcs = ["stopwatch_main.cc"],
     deps = [
-        ":flags",
         ":init_mozc",
         ":stopwatch",
         ":util",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -1381,10 +1364,10 @@ cc_test_mozc(
     deps = [
         ":file_stream",
         ":file_util",
-        ":flags",
         ":multifile",
         ":util",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -1439,8 +1422,9 @@ cc_binary_mozc(
     ],
     deps = [
         ":init_mozc",
-        ":flags",
+        ":port",
         ":util",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ] + select_mozc(ios = [":mac_util"]),
 )
@@ -1545,7 +1529,6 @@ cc_library_mozc(
         ],
         oss = [
             ":logging",
-            ":flags",
         ],
     ),
 )
diff --git base/base.gyp base/base.gyp
index 50446616f..0b87c4817 100644
--- base/base.gyp
+++ base/base.gyp
@@ -188,11 +188,8 @@
       'target_name': 'flags',
       'type': 'static_library',
       'toolsets': ['host', 'target'],
-      'sources': [
-        'flags.cc',
-      ],
       'dependencies': [
-        'singleton',
+        'absl.gyp:absl_flags',
       ],
     },
     {
diff --git base/base_test.gyp base/base_test.gyp
index d252fe60a..09a4cb2fa 100644
--- base/base_test.gyp
+++ base/base_test.gyp
@@ -101,7 +101,6 @@
       'type': 'executable',
       'sources': [
         'bitarray_test.cc',
-        'flags_test.cc',
         'iterator_adapter_test.cc',
         'logging_test.cc',
         'mmap_test.cc',
diff --git base/config_file_stream.h base/config_file_stream.h
index 17ddcf15d..7a09f850e 100644
--- base/config_file_stream.h
+++ base/config_file_stream.h
@@ -74,7 +74,7 @@ class ConfigFileStream {
   //     return Open(filename, ios_base::in);
   //   }
   // As of Mozc 1.3, a number of files had had depended on this method.
-  // However, we did not programatically replaced all of them with
+  // However, we did not programmatically replaced all of them with
   // |OpenReadText| because these existing code do not have enough unit
   // tests to check the treatment of line-end character, especially on Windows.
   // Perhaps |OpenReadBinary| might be more appropriate in some cases.
diff --git base/config_file_stream_test.cc base/config_file_stream_test.cc
index 6040f604f..29875f055 100644
--- base/config_file_stream_test.cc
+++ base/config_file_stream_test.cc
@@ -35,10 +35,10 @@
 #include <memory>
 
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/system_util.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 
@@ -61,7 +61,7 @@ std::string GetFileData(const std::string &filename) {
 // |input_stream| as a side effect.
 bool IsEof(std::istream *input_stream) {
   return (input_stream->peek() == std::istream::traits_type::eof() &&
-          // On some enviroment (e.g. Mac OS 10.8 w/ Xcode 4.5),
+          // On some environment (e.g. Mac OS 10.8 w/ Xcode 4.5),
           // peek() does not flip eofbit.  So calling get() is also
           // required.
           input_stream->get() == std::istream::traits_type::eof() &&
@@ -74,7 +74,7 @@ class ConfigFileStreamTest : public testing::Test {
  protected:
   void SetUp() override {
     default_profile_directory_ = SystemUtil::GetUserProfileDirectory();
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   }
 
   void TearDown() override {
diff --git base/cpu_stats_main.cc base/cpu_stats_main.cc
index d70e0f75c..b318d00d3 100644
--- base/cpu_stats_main.cc
+++ base/cpu_stats_main.cc
@@ -32,16 +32,16 @@
 #include <string>
 
 #include "base/cpu_stats.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/port.h"
 #include "base/thread.h"
 #include "base/util.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
-MOZC_FLAG(int32, iterations, 1000, "number of iterations");
-MOZC_FLAG(int32, polling_duration, 1000, "duration period in msec");
-MOZC_FLAG(int32, dummy_threads_size, 0, "number of dummy threads");
+ABSL_FLAG(int32, iterations, 1000, "number of iterations");
+ABSL_FLAG(int32, polling_duration, 1000, "duration period in msec");
+ABSL_FLAG(int32, dummy_threads_size, 0, "number of dummy threads");
 
 namespace {
 class DummyThread : public mozc::Thread {
@@ -65,10 +65,10 @@ int main(int argc, char **argv) {
 
   std::unique_ptr<DummyThread[]> threads;
 
-  if (mozc::GetFlag(FLAGS_dummy_threads_size) > 0) {
+  if (absl::GetFlag(FLAGS_dummy_threads_size) > 0) {
     threads = absl::make_unique<DummyThread[]>(
-        mozc::GetFlag(FLAGS_dummy_threads_size));
-    for (int i = 0; i < mozc::GetFlag(FLAGS_dummy_threads_size); ++i) {
+        absl::GetFlag(FLAGS_dummy_threads_size));
+    for (int i = 0; i < absl::GetFlag(FLAGS_dummy_threads_size); ++i) {
       threads[i].Start("CpuStatsMain");
     }
   }
@@ -76,10 +76,10 @@ int main(int argc, char **argv) {
   mozc::CPUStats stats;
   std::cout << "NumberOfProcessors: " << stats.GetNumberOfProcessors()
             << std::endl;
-  for (int i = 0; i < mozc::GetFlag(FLAGS_iterations); ++i) {
+  for (int i = 0; i < absl::GetFlag(FLAGS_iterations); ++i) {
     std::cout << "CPUStats: " << stats.GetSystemCPULoad() << " "
               << stats.GetCurrentProcessCPULoad() << std::endl;
-    mozc::Util::Sleep(mozc::GetFlag(FLAGS_polling_duration));
+    mozc::Util::Sleep(absl::GetFlag(FLAGS_polling_duration));
   }
 
   return 0;
diff --git base/encryptor_main.cc base/encryptor_main.cc
index 04790502c..4714fcf30 100644
--- base/encryptor_main.cc
+++ base/encryptor_main.cc
@@ -32,26 +32,26 @@
 
 #include "base/encryptor.h"
 #include "base/file_stream.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/mmap.h"
 #include "base/util.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, password, "", "password");
-MOZC_FLAG(string, salt, "", "salt");
-MOZC_FLAG(string, iv, "", "initialization vector");
+ABSL_FLAG(std::string, password, "", "password");
+ABSL_FLAG(std::string, salt, "", "salt");
+ABSL_FLAG(std::string, iv, "", "initialization vector");
 
-MOZC_FLAG(bool, encrypt, false, "encrypt mode");
-MOZC_FLAG(bool, decrypt, false, "decrypt mode");
+ABSL_FLAG(bool, encrypt, false, "encrypt mode");
+ABSL_FLAG(bool, decrypt, false, "decrypt mode");
 
 // encrypt/decrypt files
-MOZC_FLAG(string, input_file, "", "input file");
-MOZC_FLAG(string, output_file, "", "input file");
+ABSL_FLAG(std::string, input_file, "", "input file");
+ABSL_FLAG(std::string, output_file, "", "input file");
 
 // perform encryption/decryption with test_input.
 // used for making a golden data for unittesting
-MOZC_FLAG(string, test_input, "", "test input string");
+ABSL_FLAG(std::string, test_input, "", "test input string");
 
 namespace {
 std::string Escape(const std::string &buf) {
@@ -64,48 +64,48 @@ std::string Escape(const std::string &buf) {
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
-  if (!mozc::GetFlag(FLAGS_iv).empty()) {
-    CHECK_EQ(16, mozc::GetFlag(FLAGS_iv).size()) << "iv size must be 16 byte";
+  if (!absl::GetFlag(FLAGS_iv).empty()) {
+    CHECK_EQ(16, absl::GetFlag(FLAGS_iv).size()) << "iv size must be 16 byte";
   }
 
-  const std::string iv_str = mozc::GetFlag(FLAGS_iv);
+  const std::string iv_str = absl::GetFlag(FLAGS_iv);
   const uint8 *iv =
       iv_str.empty() ? nullptr : reinterpret_cast<const uint8 *>(iv_str.data());
 
-  if (!mozc::GetFlag(FLAGS_input_file).empty() &&
-      !mozc::GetFlag(FLAGS_output_file).empty()) {
+  if (!absl::GetFlag(FLAGS_input_file).empty() &&
+      !absl::GetFlag(FLAGS_output_file).empty()) {
     mozc::Encryptor::Key key;
-    CHECK(key.DeriveFromPassword(mozc::GetFlag(FLAGS_password),
-                                 mozc::GetFlag(FLAGS_salt), iv));
+    CHECK(key.DeriveFromPassword(absl::GetFlag(FLAGS_password),
+                                 absl::GetFlag(FLAGS_salt), iv));
 
     mozc::Mmap mmap;
-    CHECK(mmap.Open(mozc::GetFlag(FLAGS_input_file).c_str(), "r"));
+    CHECK(mmap.Open(absl::GetFlag(FLAGS_input_file).c_str(), "r"));
     std::string buf(mmap.begin(), mmap.size());
-    if (mozc::GetFlag(FLAGS_encrypt)) {
+    if (absl::GetFlag(FLAGS_encrypt)) {
       CHECK(mozc::Encryptor::EncryptString(key, &buf));
-    } else if (mozc::GetFlag(FLAGS_decrypt)) {
+    } else if (absl::GetFlag(FLAGS_decrypt)) {
       CHECK(mozc::Encryptor::DecryptString(key, &buf));
     } else {
       LOG(FATAL) << "unknown mode. set --encrypt or --decrypt";
     }
-    mozc::OutputFileStream ofs(mozc::GetFlag(FLAGS_output_file).c_str(),
+    mozc::OutputFileStream ofs(absl::GetFlag(FLAGS_output_file).c_str(),
                                std::ios::binary);
     CHECK(ofs);
     ofs.write(buf.data(), buf.size());
-  } else if (!mozc::GetFlag(FLAGS_test_input).empty()) {
+  } else if (!absl::GetFlag(FLAGS_test_input).empty()) {
     mozc::Encryptor::Key key1, key2;
-    CHECK(key1.DeriveFromPassword(mozc::GetFlag(FLAGS_password),
-                                  mozc::GetFlag(FLAGS_salt), iv));
-    CHECK(key2.DeriveFromPassword(mozc::GetFlag(FLAGS_password),
-                                  mozc::GetFlag(FLAGS_salt), iv));
+    CHECK(key1.DeriveFromPassword(absl::GetFlag(FLAGS_password),
+                                  absl::GetFlag(FLAGS_salt), iv));
+    CHECK(key2.DeriveFromPassword(absl::GetFlag(FLAGS_password),
+                                  absl::GetFlag(FLAGS_salt), iv));
 
-    std::string buf = mozc::GetFlag(FLAGS_test_input);
+    std::string buf = absl::GetFlag(FLAGS_test_input);
     std::string iv_buf(reinterpret_cast<const char *>(key1.iv()),
                        key1.iv_size());
 
-    std::cout << "Password:  \"" << Escape(mozc::GetFlag(FLAGS_password))
+    std::cout << "Password:  \"" << Escape(absl::GetFlag(FLAGS_password))
               << "\"" << std::endl;
-    std::cout << "Salt:      \"" << Escape(mozc::GetFlag(FLAGS_salt)) << "\""
+    std::cout << "Salt:      \"" << Escape(absl::GetFlag(FLAGS_salt)) << "\""
               << std::endl;
     std::cout << "IV:        \"" << Escape(iv_buf) << "\"" << std::endl;
     std::cout << "Input:     \"" << Escape(buf) << "\"" << std::endl;
diff --git base/encryptor_test.cc base/encryptor_test.cc
index d992ea901..9f9553a4e 100644
--- base/encryptor_test.cc
+++ base/encryptor_test.cc
@@ -31,12 +31,12 @@
 
 #include <memory>
 
-#include "base/flags.h"
 #include "base/password_manager.h"
 #include "base/system_util.h"
 #include "base/util.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 
@@ -226,7 +226,7 @@ TEST(EncryptorTest, EncryptBatch) {
 }
 
 TEST(EncryptorTest, ProtectData) {
-  SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+  SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   const size_t kSizeTable[] = {1, 10, 100, 1000, 10000, 100000};
 
   for (size_t i = 0; i < arraysize(kSizeTable); ++i) {
diff --git base/file_util_test.cc base/file_util_test.cc
index 1a11e2c5c..7251d2821 100644
--- base/file_util_test.cc
+++ base/file_util_test.cc
@@ -37,11 +37,11 @@
 #include <string>
 
 #include "base/file_stream.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/util.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 // Ad-hoc workadound against macro problem on Windows.
 // On Windows, following macros, defined when you include <Windows.h>,
@@ -71,10 +71,10 @@ void CreateTestFile(const std::string &filename, const std::string &data) {
 }  // namespace
 
 TEST_F(FileUtilTest, CreateDirectory) {
-  EXPECT_TRUE(FileUtil::DirectoryExists(mozc::GetFlag(FLAGS_test_tmpdir)));
+  EXPECT_TRUE(FileUtil::DirectoryExists(absl::GetFlag(FLAGS_test_tmpdir)));
   // dirpath = FLAGS_test_tmpdir/testdir
   const std::string dirpath =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "testdir");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "testdir");
 
   // Delete dirpath, if it exists.
   if (FileUtil::FileExists(dirpath)) {
@@ -92,9 +92,9 @@ TEST_F(FileUtilTest, CreateDirectory) {
 }
 
 TEST_F(FileUtilTest, DirectoryExists) {
-  EXPECT_TRUE(FileUtil::DirectoryExists(mozc::GetFlag(FLAGS_test_tmpdir)));
+  EXPECT_TRUE(FileUtil::DirectoryExists(absl::GetFlag(FLAGS_test_tmpdir)));
   const std::string filepath =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "testfile");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "testfile");
 
   // Delete filepath, if it exists.
   if (FileUtil::FileExists(filepath)) {
@@ -114,7 +114,7 @@ TEST_F(FileUtilTest, DirectoryExists) {
 
 TEST_F(FileUtilTest, Unlink) {
   const std::string filepath =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "testfile");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "testfile");
   FileUtil::Unlink(filepath);
   EXPECT_FALSE(FileUtil::FileExists(filepath));
 
@@ -150,7 +150,7 @@ TEST_F(FileUtilTest, Unlink) {
 #ifdef OS_WIN
 TEST_F(FileUtilTest, HideFile) {
   const string filename =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "testfile");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "testfile");
   FileUtil::Unlink(filename);
 
   EXPECT_FALSE(FileUtil::HideFile(filename));
@@ -198,9 +198,9 @@ TEST_F(FileUtilTest, HideFile) {
 
 TEST_F(FileUtilTest, IsEqualFile) {
   const std::string filename1 =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "test1");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "test1");
   const std::string filename2 =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "test2");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "test2");
   FileUtil::Unlink(filename1);
   FileUtil::Unlink(filename2);
   EXPECT_FALSE(FileUtil::IsEqualFile(filename1, filename2));
@@ -224,9 +224,9 @@ TEST_F(FileUtilTest, IsEqualFile) {
 TEST_F(FileUtilTest, CopyFile) {
   // just test rename operation works as intended
   const std::string from =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "copy_from");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "copy_from");
   const std::string to =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "copy_to");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "copy_to");
   FileUtil::Unlink(from);
   FileUtil::Unlink(to);
 
@@ -292,9 +292,9 @@ TEST_F(FileUtilTest, CopyFile) {
 
 TEST_F(FileUtilTest, AtomicRename) {
   // just test rename operation works as intended
-  const std::string from = FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir),
+  const std::string from = FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir),
                                               "atomic_rename_test_from");
-  const std::string to = FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir),
+  const std::string to = FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir),
                                             "atomic_rename_test_to");
   FileUtil::Unlink(from);
   FileUtil::Unlink(to);
@@ -455,7 +455,7 @@ TEST_F(FileUtilTest, GetModificationTime) {
   EXPECT_FALSE(FileUtil::GetModificationTime("not_existent_file", &time_stamp));
 
   const std::string &path =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "testfile");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "testfile");
   CreateTestFile(path, "content");
   EXPECT_TRUE(FileUtil::GetModificationTime(path, &time_stamp));
   EXPECT_NE(0, time_stamp);
diff --git base/flags.cc base/flags.cc
deleted file mode 100644
index b01f56893..000000000
--- base/flags.cc
+++ /dev/null
@@ -1,320 +0,0 @@
-// Copyright 2010-2021, Google Inc.
-// All rights reserved.
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//     * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-#include "base/flags.h"
-
-#include <cstring>
-#include <iostream>
-#include <map>
-#include <sstream>
-#include <string>
-#include <vector>
-
-#include "base/port.h"
-#include "base/singleton.h"
-
-namespace mozc_flags {
-
-struct Flag {
-  int type;
-  void *storage;
-  const void *default_storage;
-  string help;
-};
-
-namespace {
-
-typedef std::map<string, mozc_flags::Flag *> FlagMap;
-
-FlagMap *GetFlagMap() { return mozc::Singleton<FlagMap>::get(); }
-
-bool IsTrue(const char *value) {
-  const char *kTrue[] = {"1", "t", "true", "y", "yes"};
-  const char *kFalse[] = {"0", "f", "false", "n", "no"};
-  for (size_t i = 0; i < arraysize(kTrue); ++i) {
-    if (strcmp(value, kTrue[i]) == 0) {
-      return true;
-    } else if (strcmp(value, kFalse[i]) == 0) {
-      return false;
-    }
-  }
-  return false;
-}
-
-// Wraps std::sto* functions by a template class so that appropriate functions
-// are chosen for platform-dependent integral types by type deduction.  For
-// example, if int64 is defined as long long, then StrToNumberImpl<int64>::Do()
-// is mapped to StrToNumberImpl::Do<long long>().  Here, struct (class) is
-// intentionally used instead of a template function because, if we use a
-// function, compiler may warn of "unused function".
-template <typename T>
-struct StrToNumberImpl;
-
-template <>
-struct StrToNumberImpl<int> {
-  static int Do(const string &s) { return std::stoi(s); }
-};
-
-template <>
-struct StrToNumberImpl<long> {                              // NOLINT
-  static long Do(const string &s) { return std::stol(s); }  // NOLINT
-};
-
-template <>
-struct StrToNumberImpl<long long> {                               // NOLINT
-  static long long Do(const string &s) { return std::stoll(s); }  // NOLINT
-};
-
-template <>
-struct StrToNumberImpl<unsigned long> {                               // NOLINT
-  static unsigned long Do(const string &s) { return std::stoul(s); }  // NOLINT
-};
-
-template <>
-struct StrToNumberImpl<unsigned long long> {       // NOLINT
-  static unsigned long long Do(const string &s) {  // NOLINT
-    return std::stoull(s);
-  }
-};
-
-template <typename T>
-inline T StrToNumber(const string &s) {
-  return StrToNumberImpl<T>::Do(s);
-}
-
-#if defined(DEBUG) || defined(__APPLE__)
-// Defines std::string version of absl::string_view::starts_with here to make
-// flags module from independent of string_piece.cc because absl::string_view
-// depends on logging.cc etc. and using it causes cyclic dependency.
-inline bool StartsWith(const string &s, const string &prefix) {
-  return s.size() >= prefix.size() &&
-         memcmp(s.data(), prefix.data(), prefix.size()) == 0;
-}
-#endif  // defined(DEBUG) || defined(__APPLE__)
-
-}  // namespace
-
-FlagRegister::FlagRegister(const char *name, void *storage,
-                           const void *default_storage, int shorttpe,
-                           const char *help)
-    : flag_(new Flag) {
-  flag_->type = shorttpe;
-  flag_->storage = storage;
-  flag_->default_storage = default_storage;
-  flag_->help = help;
-  GetFlagMap()->insert(std::make_pair(string(name), flag_));
-}
-
-FlagRegister::~FlagRegister() { delete flag_; }
-
-bool SetFlag(const string &name, const string &value) {
-  std::map<string, Flag *>::iterator it = GetFlagMap()->find(name);
-  if (it == GetFlagMap()->end()) return false;
-  string v = value;
-  Flag *flag = it->second;
-
-  // If empty value is set, we assume true or empty string is set
-  // for boolean or string option. With other types, setting fails.
-  if (value.empty()) {
-    switch (flag->type) {
-      case B:
-        v = "true";
-        break;
-      case S:
-        v = "";
-        break;
-      default:
-        return false;
-    }
-  }
-
-  switch (flag->type) {
-    case I:
-      *reinterpret_cast<int32 *>(flag->storage) = StrToNumber<int32>(v);
-      break;
-    case B:
-      *(reinterpret_cast<bool *>(flag->storage)) = IsTrue(v.c_str());
-      break;
-    case I64:
-      *reinterpret_cast<int64 *>(flag->storage) = StrToNumber<int64>(v);
-      break;
-    case U64:
-      *reinterpret_cast<uint64 *>(flag->storage) = StrToNumber<uint64>(v);
-      break;
-    case D:
-      *reinterpret_cast<double *>(flag->storage) = strtod(v.c_str(), nullptr);
-      break;
-    case S:
-      *reinterpret_cast<string *>(flag->storage) = v;
-      break;
-    default:
-      break;
-  }
-  return true;
-}
-
-namespace {
-
-#ifndef IGNORE_HELP_FLAG
-
-void PrintFlags(string *output) {
-  std::ostringstream os;
-  for (std::map<string, Flag *>::const_iterator it = GetFlagMap()->begin();
-       it != GetFlagMap()->end(); ++it) {
-    os << "   --" << it->first << " (" << it->second->help << ")";
-    const Flag *flag = it->second;
-    switch (flag->type) {
-      case I:
-        os << "  type: int32  default: "
-           << *(reinterpret_cast<const int *>(flag->default_storage))
-           << std::endl;
-        break;
-      case B:
-        os << "  type: bool  default: "
-           << (*(reinterpret_cast<const bool *>(flag->default_storage))
-                   ? "true"
-                   : "false")
-           << std::endl;
-        break;
-      case I64:
-        os << "  type: int64 default: "
-           << *(reinterpret_cast<const int64 *>(flag->default_storage))
-           << std::endl;
-        break;
-      case U64:
-        os << "  type: uint64  default: "
-           << *(reinterpret_cast<const uint64 *>(flag->default_storage))
-           << std::endl;
-        break;
-      case D:
-        os << "  type: double  default: "
-           << *(reinterpret_cast<const double *>(flag->default_storage))
-           << std::endl;
-        break;
-      case S:
-        os << "  type: string  default: "
-           << *(reinterpret_cast<const string *>(flag->default_storage))
-           << std::endl;
-        break;
-      default:
-        break;
-    }
-  }
-  *output = os.str();
-}
-
-#endif  // IGNORE_HELP_FLAG
-
-bool CommandLineGetFlag(int argc, char **argv, string *key, string *value,
-                        int *used_args) {
-  key->clear();
-  value->clear();
-  *used_args = 0;
-  if (argc < 1) {
-    return false;
-  }
-
-  *used_args = 1;
-  const char *start = argv[0];
-  if (start[0] != '-') {
-    return false;
-  }
-
-  ++start;
-  if (start[0] == '-') ++start;
-  const string arg = start;
-  const size_t n = arg.find("=");
-  if (n != string::npos) {
-    *key = arg.substr(0, n);
-    *value = arg.substr(n + 1, arg.size() - n);
-    return true;
-  }
-
-  key->assign(arg);
-  value->clear();
-
-  if (argc == 1) {
-    return true;
-  }
-  start = argv[1];
-  if (start[0] == '-') {
-    return true;
-  }
-
-  *used_args = 2;
-  value->assign(start);
-  return true;
-}
-
-}  // namespace
-
-uint32 ParseCommandLineFlags(int *argc, char ***argv) {
-  int used_argc = 0;
-  string key, value;
-  for (int i = 1; i < *argc; i += used_argc) {
-    if (!CommandLineGetFlag(*argc - i, *argv + i, &key, &value, &used_argc)) {
-      // TODO(komatsu): Do error handling
-      continue;
-    }
-
-    if (key == "help") {
-#ifndef IGNORE_HELP_FLAG
-      string help;
-      PrintFlags(&help);
-      std::cout << help;
-      exit(0);
-#endif
-    }
-#ifdef DEBUG
-    // Ignores unittest specific commandline flags.
-    // In the case of Release build, IGNORE_INVALID_FLAG macro is set, so that
-    // following condition makes no sense.
-    if (StartsWith(key, "gtest_") || StartsWith(key, "gunit_")) {
-      continue;
-    }
-#endif  // DEBUG
-#ifdef __APPLE__
-    // Mac OSX specifies process serial number like -psn_0_217141.
-    // Let's ignore it.
-    if (StartsWith(key, "psn_")) {
-      continue;
-    }
-#endif
-    if (!SetFlag(key, value)) {
-#ifndef IGNORE_INVALID_FLAG
-      std::cerr << "Unknown/Invalid flag " << key << std::endl;
-      exit(1);
-#endif
-    }
-  }
-  return *argc;
-}
-
-}  // namespace mozc_flags
-
diff --git base/flags.h base/flags.h
index 3bd878fa2..9e5ea80b9 100644
--- base/flags.h
+++ base/flags.h
@@ -33,94 +33,7 @@
 #define MOZC_BASE_FLAGS_H_
 
 #include "base/port.h"
-
-#include <string>
-
-namespace mozc_flags {
-
-enum { I, B, I64, U64, D, S };
-
-struct Flag;
-
-class FlagRegister {
- public:
-  FlagRegister(const char *name, void *storage, const void *default_storage,
-               int shorttpe, const char *help);
-  ~FlagRegister();
-
- private:
-  Flag *flag_;
-};
-
-uint32 ParseCommandLineFlags(int *argc, char ***argv);
-bool SetFlag(const string &key, const string &value);
-
-}  // namespace mozc_flags
-
-#define DEFINE_VARIABLE(type, shorttype, name, value, help)               \
-  namespace mozc_flags_fL##shorttype {                                    \
-    using mozc_flags::shorttype;                                          \
-    type FLAGS_##name = value;                                            \
-    static const type FLAGS_DEFAULT_##name = value;                       \
-    static const mozc_flags::FlagRegister fL##name(                       \
-        #name, reinterpret_cast<void *>(&FLAGS_##name),                   \
-        reinterpret_cast<const void *>(&FLAGS_DEFAULT_##name), shorttype, \
-        help);                                                            \
-  }                                                                       \
-  using mozc_flags_fL##shorttype::FLAGS_##name
-
-#define DECLARE_VARIABLE(type, shorttype, name) \
-  namespace mozc_flags_fL##shorttype {          \
-    extern type FLAGS_##name;                   \
-  }                                             \
-  using mozc_flags_fL##shorttype::FLAGS_##name
-
-#define DEFINE_int32(name, value, help) \
-  DEFINE_VARIABLE(int32, I, name, value, help)
-#define DECLARE_int32(name) DECLARE_VARIABLE(int32, I, name)
-
-#define DEFINE_int64(name, value, help) \
-  DEFINE_VARIABLE(int64, I64, name, value, help)
-#define DECLARE_int64(name) DECLARE_VARIABLE(int64, I64, name)
-
-#define DEFINE_uint64(name, value, help) \
-  DEFINE_VARIABLE(uint64, U64, name, value, help)
-#define DECLARE_uint64(name) DECLARE_VARIABLE(uint64, U64, name)
-
-#define DEFINE_double(name, value, help) \
-  DEFINE_VARIABLE(double, D, name, value, help)
-#define DECLARE_double(name) DECLARE_VARIABLE(double, D, name)
-
-#define DEFINE_bool(name, value, help) \
-  DEFINE_VARIABLE(bool, B, name, value, help)
-#define DECLARE_bool(name) DECLARE_VARIABLE(bool, B, name)
-
-#define DEFINE_string(name, value, help) \
-  DEFINE_VARIABLE(string, S, name, value, help)
-#define DECLARE_string(name) DECLARE_VARIABLE(string, S, name)
-
-#define MOZC_FLAG(type, name, value, help) \
-  DEFINE_##type(name, value, help)
-
-#define MOZC_DECLARE_FLAG(type, name) \
-  DECLARE_##type(name)
-
-namespace mozc {
-
-inline bool GetFlag(bool flag) { return flag; }
-inline int32 GetFlag(int32 flag) { return flag; }
-inline int64 GetFlag(int64 flag) { return flag; }
-inline uint64 GetFlag(uint64 flag) { return flag; }
-inline double GetFlag(double flag) { return flag; }
-inline string GetFlag(const string &flag) { return flag; }
-
-inline void SetFlag(bool *f, bool v) { *f = v; }
-inline void SetFlag(int32 *f, int32 v) { *f = v; }
-inline void SetFlag(int64 *f, int64 v) { *f = v; }
-inline void SetFlag(uint64 *f, uint64 v) { *f = v; }
-inline void SetFlag(double *f, double v) { *f = v; }
-inline void SetFlag(string *f, const string &v) { *f = v; }
-
-}  // namespace mozc
+#include "absl/flags/declare.h"
+#include "absl/flags/flag.h"
 
 #endif  // MOZC_BASE_FLAGS_H_
diff --git base/flags_test.cc base/flags_test.cc
deleted file mode 100644
index 4453a8754..000000000
--- base/flags_test.cc
+++ /dev/null
@@ -1,157 +0,0 @@
-// Copyright 2010-2021, Google Inc.
-// All rights reserved.
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//     * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-#include "base/flags.h"
-
-#include <cstring>
-
-#include "testing/base/public/gunit.h"
-
-using std::string;
-
-MOZC_FLAG(string, test_string, "hogehoge", "test_string");
-MOZC_FLAG(int32, test_int32, 20, "test_int32");
-MOZC_FLAG(int64, test_int64, 29051773239673121LL, "test_int64");
-MOZC_FLAG(uint64, test_uint64, 84467440737095516LL, "test_uint64");
-MOZC_FLAG(bool, test_bool, false, "test_bool");
-MOZC_FLAG(double, test_double, 0.5, "test_double");
-
-namespace mozc {
-namespace {
-
-char *strdup_with_new(const char *str) {
-  char *result = new char[strlen(str) + 1];
-  strcpy(result, str);
-  return result;
-}
-
-class FlagsTest : public testing::Test {
- protected:
-  void SetUp() override {
-    mozc::SetFlag(&FLAGS_test_string, "hogehoge");
-    mozc::SetFlag(&FLAGS_test_int32, 20);
-    mozc::SetFlag(&FLAGS_test_int64, 29051773239673121LL);
-    mozc::SetFlag(&FLAGS_test_uint64, 84467440737095516LL);
-    mozc::SetFlag(&FLAGS_test_bool, false);
-    mozc::SetFlag(&FLAGS_test_double, 0.5);
-  }
-};
-
-TEST_F(FlagsTest, FlagsBasicTest) {
-  EXPECT_FALSE(mozc::GetFlag(FLAGS_test_bool));
-  EXPECT_EQ(20, mozc::GetFlag(FLAGS_test_int32));
-  EXPECT_EQ(int64{29051773239673121}, mozc::GetFlag(FLAGS_test_int64));
-  EXPECT_EQ(int64{84467440737095516}, mozc::GetFlag(FLAGS_test_uint64));
-  EXPECT_EQ("hogehoge", mozc::GetFlag(FLAGS_test_string));
-  EXPECT_LT(0.4, mozc::GetFlag(FLAGS_test_double));
-  EXPECT_GT(0.6, mozc::GetFlag(FLAGS_test_double));
-
-  char **argv = new char *[8];
-  argv[0] = strdup_with_new("test");
-  argv[1] = strdup_with_new("--test_int32=11214141");
-  argv[2] = strdup_with_new("--test_string=test");
-  argv[3] = strdup_with_new("--test_bool=true");
-  argv[4] = strdup_with_new("--test_double=1.5");
-  argv[5] = strdup_with_new("--test_int64=8172141141413124");
-  argv[6] = strdup_with_new("--test_uint64=9414041694169841");
-  argv[7] = strdup_with_new("invalid_value");
-  int argc = 8;
-  const uint32 used_argc = mozc_flags::ParseCommandLineFlags(&argc, &argv);
-  for (size_t i = 0; i < argc; ++i) {
-    delete[] argv[i];
-  }
-  delete[] argv;
-
-  EXPECT_EQ(8u, used_argc);
-  EXPECT_EQ(true, mozc::GetFlag(FLAGS_test_bool));
-  EXPECT_EQ(11214141, mozc::GetFlag(FLAGS_test_int32));
-  EXPECT_EQ(8172141141413124LL, mozc::GetFlag(FLAGS_test_int64));
-  EXPECT_EQ(9414041694169841LL, mozc::GetFlag(FLAGS_test_uint64));
-  EXPECT_EQ("test", mozc::GetFlag(FLAGS_test_string));
-  EXPECT_LT(1.4, mozc::GetFlag(FLAGS_test_double));
-  EXPECT_GT(1.6, mozc::GetFlag(FLAGS_test_double));
-}
-
-TEST_F(FlagsTest, NoValuesFlagsTest) {
-  EXPECT_FALSE(mozc::GetFlag(FLAGS_test_bool));
-  EXPECT_EQ(20, mozc::GetFlag(FLAGS_test_int32));
-  EXPECT_EQ(int64{29051773239673121}, mozc::GetFlag(FLAGS_test_int64));
-  EXPECT_EQ(int64{84467440737095516}, mozc::GetFlag(FLAGS_test_uint64));
-  EXPECT_EQ("hogehoge", mozc::GetFlag(FLAGS_test_string));
-  EXPECT_LT(0.4, mozc::GetFlag(FLAGS_test_double));
-  EXPECT_GT(0.6, mozc::GetFlag(FLAGS_test_double));
-
-  char **argv = new char *[3];
-  // We set only boolean and string values, because other types will stops
-  // the test process if empty values are set.
-  argv[0] = strdup_with_new("test");
-  argv[1] = strdup_with_new("--test_string");
-  argv[2] = strdup_with_new("--test_bool");
-  int argc = 3;
-  const uint32 used_argc = mozc_flags::ParseCommandLineFlags(&argc, &argv);
-  for (size_t i = 0; i < argc; ++i) {
-    delete[] argv[i];
-  }
-  delete[] argv;
-
-  EXPECT_EQ(3u, used_argc);
-  EXPECT_TRUE(mozc::GetFlag(FLAGS_test_bool));
-  EXPECT_EQ("", mozc::GetFlag(FLAGS_test_string));
-  // Following values are kept as default.
-  EXPECT_EQ(20, mozc::GetFlag(FLAGS_test_int32));
-  EXPECT_EQ(29051773239673121LL, mozc::GetFlag(FLAGS_test_int64));
-  EXPECT_EQ(84467440737095516LL, mozc::GetFlag(FLAGS_test_uint64));
-  EXPECT_LT(0.4, mozc::GetFlag(FLAGS_test_double));
-  EXPECT_GT(0.6, mozc::GetFlag(FLAGS_test_double));
-}
-
-TEST_F(FlagsTest, SetFlag) {
-  mozc_flags::SetFlag("test_bool", "true");
-  EXPECT_TRUE(mozc::GetFlag(FLAGS_test_bool));
-  mozc_flags::SetFlag("test_bool", "false");
-  EXPECT_FALSE(mozc::GetFlag(FLAGS_test_bool));
-
-  mozc_flags::SetFlag("test_int32", "12345");
-  EXPECT_EQ(12345, mozc::GetFlag(FLAGS_test_int32));
-
-  mozc_flags::SetFlag("test_int64", "10000000000000000");
-  EXPECT_EQ(10000000000000000LL, mozc::GetFlag(FLAGS_test_int64));
-
-  mozc_flags::SetFlag("test_uint64", "50000000000000000");
-  EXPECT_EQ(50000000000000000LL, mozc::GetFlag(FLAGS_test_uint64));
-
-  mozc_flags::SetFlag("test_string", "Tokyo");
-  EXPECT_EQ("Tokyo", mozc::GetFlag(FLAGS_test_string));
-
-  mozc_flags::SetFlag("test_double", "3.14");
-  EXPECT_DOUBLE_EQ(3.14, mozc::GetFlag(FLAGS_test_double));
-}
-
-}  // namespace
-}  // namespace mozc
diff --git base/gen_character_set.py base/gen_character_set.py
index 87a36e280..2b6b588a2 100644
--- base/gen_character_set.py
+++ base/gen_character_set.py
@@ -145,7 +145,7 @@ def _LoadExceptions():
         0x301C,  # WAVE DASH
         0xFF5E,  # FULL WIDTH TILDE
         0x2016,  # DOUBLE VERTICAL LINE
-        0x2225,  # PARALEL TO
+        0x2225,  # PARALLEL TO
         0x2212,  # MINUS SIGN
         0xFF0D,  # FULL WIDTH HYPHEN MINUS
         0x00A2,  # CENT SIGN
diff --git base/init_mozc.cc base/init_mozc.cc
index 010341048..eee8b6226 100644
--- base/init_mozc.cc
+++ base/init_mozc.cc
@@ -29,37 +29,40 @@
 
 #include "base/init_mozc.h"
 
-
 #ifdef OS_WIN
 #include <windows.h>
 #endif  // OS_WIN
 
 #include <string>
 
-#include "base/file_util.h"
-
-
-#include "base/flags.h"
 
+#include "base/file_util.h"
 #include "base/logging.h"
+
 #ifndef MOZC_BUILDTOOL_BUILD
 #include "base/system_util.h"
 #endif  // MOZC_BUILDTOOL_BUILD
 
+
+#include "absl/flags/flag.h"
+
+#include "absl/flags/parse.h"
+
 // Even if log_dir is modified in the middle of the process, the
 // logging directory will not be changed because the logging stream is
 // initialized in the very early initialization stage.
-MOZC_FLAG(string, log_dir, "",
+ABSL_FLAG(std::string, log_dir, "",
           "If specified, logfiles are written into this directory "
           "instead of the default logging directory.");
 
 
-MOZC_FLAG(string, program_invocation_name, "",
+ABSL_FLAG(std::string, program_invocation_name, "",
           "Program name copied from argv[0].");
 
 namespace mozc {
 namespace {
 
+
 #ifdef OS_WIN
 LONG CALLBACK ExitProcessExceptionFilter(EXCEPTION_POINTERS *ExceptionInfo) {
   // Currently, we haven't found a good way to perform both
@@ -69,22 +72,33 @@ LONG CALLBACK ExitProcessExceptionFilter(EXCEPTION_POINTERS *ExceptionInfo) {
 }
 #endif  // OS_WIN
 
-string GetLogFilePathFromProgramName(const string &program_name) {
-  const string basename = FileUtil::Basename(program_name) + ".log";
-  if (mozc::GetFlag(FLAGS_log_dir).empty()) {
+std::string GetLogFilePathFromProgramName(const std::string &program_name) {
+  const std::string basename = FileUtil::Basename(program_name) + ".log";
+  if (absl::GetFlag(FLAGS_log_dir).empty()) {
 #ifdef MOZC_BUILDTOOL_BUILD
     return basename;
 #else   // MOZC_BUILDTOOL_BUILD
     return FileUtil::JoinPath(SystemUtil::GetLoggingDirectory(), basename);
 #endif  // MOZC_BUILDTOOL_BUILD
   }
-  return FileUtil::JoinPath(mozc::GetFlag(FLAGS_log_dir), basename);
+  return FileUtil::JoinPath(absl::GetFlag(FLAGS_log_dir), basename);
 }
 
+void ParseCommandLineFlags(int argc, char **argv) {
+  absl::flags_internal::ParseCommandLineImpl(
+      argc, argv,
+      absl::flags_internal::ArgvListAction::kRemoveParsedArgs,
+      // Suppress help messages invoked by --help and others.
+      // Use UsageFlagsAction::kHandleUsage to enable it.
+      absl::flags_internal::UsageFlagsAction::kIgnoreUsage,
+      absl::flags_internal::OnUndefinedFlag::kIgnoreUndefined);
+}
+
+
 }  // namespace
 
 void InitMozc(const char *arg0, int *argc, char ***argv) {
-  mozc::SetFlag(&FLAGS_program_invocation_name, *argv[0]);
+  absl::SetFlag(&FLAGS_program_invocation_name, *argv[0]);
 #ifdef OS_WIN
   // InitMozc() is supposed to be used for code generator or
   // other programs which are not included in the production code.
@@ -93,9 +107,9 @@ void InitMozc(const char *arg0, int *argc, char ***argv) {
   // our continuous build stable.
   ::SetUnhandledExceptionFilter(ExitProcessExceptionFilter);
 #endif  // OS_WIN
-  mozc_flags::ParseCommandLineFlags(argc, argv);
+  ParseCommandLineFlags(*argc, *argv);
 
-  const string program_name = *argc > 0 ? (*argv)[0] : "UNKNOWN";
+  const std::string program_name = *argc > 0 ? (*argv)[0] : "UNKNOWN";
   Logging::InitLogStream(GetLogFilePathFromProgramName(program_name));
 
 }
diff --git base/logging.cc base/logging.cc
index 2ef09dfdc..a00a1badc 100644
--- base/logging.cc
+++ base/logging.cc
@@ -57,16 +57,16 @@
 #include "base/const.h"
 #endif  // OS_ANDROID
 #include "base/clock.h"
-#include "base/flags.h"
 #include "base/mutex.h"
 #include "base/singleton.h"
+#include "absl/flags/flag.h"
 #include "absl/strings/str_cat.h"
 
-MOZC_FLAG(bool, colored_log, true,
+ABSL_FLAG(bool, colored_log, true,
           "Enables colored log messages on tty devices");
-MOZC_FLAG(bool, logtostderr, false,
+ABSL_FLAG(bool, logtostderr, false,
           "log messages go to stderr instead of logfiles");
-MOZC_FLAG(int32, v, 0, "verbose level");
+ABSL_FLAG(int32, v, 0, "verbose level");
 
 namespace mozc {
 
@@ -176,12 +176,12 @@ class LogStreamImpl {
   void Reset();
 
   int verbose_level() const {
-    return std::max(mozc::GetFlag(FLAGS_v), config_verbose_level_);
+    return std::max(absl::GetFlag(FLAGS_v), config_verbose_level_);
   }
 
   void set_verbose_level(int level) {
     scoped_lock l(&mutex_);
-    mozc::SetFlag(&FLAGS_v, level);
+    absl::SetFlag(&FLAGS_v, level);
   }
 
   void set_config_verbose_level(int level) {
@@ -273,11 +273,11 @@ void LogStreamImpl::Reset() {
   // Coloring is disabled on windows
   // because cmd.exe doesn't support ANSI color escape sequences.
   // TODO(team): Considers to use SetConsoleTextAttribute on Windows.
-  use_cerr_ = mozc::GetFlag(FLAGS_logtostderr);
+  use_cerr_ = absl::GetFlag(FLAGS_logtostderr);
   support_color_ = false;
 #else   // OS_ANDROID, OS_WIN
-  use_cerr_ = mozc::GetFlag(FLAGS_logtostderr);
-  support_color_ = (use_cerr_ && mozc::GetFlag(FLAGS_colored_log) &&
+  use_cerr_ = absl::GetFlag(FLAGS_logtostderr);
+  support_color_ = (use_cerr_ && absl::GetFlag(FLAGS_colored_log) &&
                     ::isatty(::fileno(stderr)));
 #endif  // OS_ANDROID, OS_WIN
 }
diff --git base/logging.h base/logging.h
index 180bf552e..5283af14f 100644
--- base/logging.h
+++ base/logging.h
@@ -34,8 +34,8 @@
 #include <iostream>
 #include <string>
 
-#include "base/flags.h"
 #include "base/port.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 
diff --git base/mac_util.h base/mac_util.h
index bf512ba89..1bc4a508a 100644
--- base/mac_util.h
+++ base/mac_util.h
@@ -55,7 +55,7 @@ class MacUtil {
   // Returns server directory using OS-specific API.
   static string GetServerDirectory();
 
-  // Returns the "Resouces/" directory in the current application.
+  // Returns the "Resources/" directory in the current application.
   static string GetResourcesDirectory();
 
   // Returns the machine serial number.
@@ -83,7 +83,7 @@ class MacUtil {
   // Returns false if an error occurred.
   static bool GetFrontmostWindowNameAndOwner(string *name, string *owner);
 
-  // Returns true when Mozc's suggestion UI is expected to be surpressed on
+  // Returns true when Mozc's suggestion UI is expected to be suppressed on
   // the window specified by |name| and |owner|.
   static bool IsSuppressSuggestionWindow(const string &name,
                                          const string &owner);
diff --git base/mac_util_main.cc base/mac_util_main.cc
index ba0fb87d1..1632e1ea3 100644
--- base/mac_util_main.cc
+++ base/mac_util_main.cc
@@ -31,27 +31,27 @@
 #include <string>
 #include <vector>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/mac_util.h"
 #include "base/util.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(bool, label_for_suffix, false,
+ABSL_FLAG(bool, label_for_suffix, false,
           "call GetLabelForSuffix when specified");
-MOZC_FLAG(bool, application_support_directory, false,
+ABSL_FLAG(bool, application_support_directory, false,
           "call GetApplicationSupportDirectory when specified");
-MOZC_FLAG(bool, logging_directory, false,
+ABSL_FLAG(bool, logging_directory, false,
           "call GetLoggingDirectory when specified");
-MOZC_FLAG(bool, os_version_string, false,
+ABSL_FLAG(bool, os_version_string, false,
           "call GetOSVersionString when specified");
-MOZC_FLAG(bool, server_directory, false,
+ABSL_FLAG(bool, server_directory, false,
           "call GetServerDirectory when specified");
-MOZC_FLAG(bool, serial_number, false, "call GetSerialNumber when specified");
-MOZC_FLAG(bool, start_launchd_service, false,
+ABSL_FLAG(bool, serial_number, false, "call GetSerialNumber when specified");
+ABSL_FLAG(bool, start_launchd_service, false,
           "call StartLaunchdService when specified");
 
-MOZC_FLAG(string, suffix, "", "The argument for GetLabelForSuffix");
-MOZC_FLAG(string, service_name, "", "The service name to be launched");
+ABSL_FLAG(std::string, suffix, "", "The argument for GetLabelForSuffix");
+ABSL_FLAG(std::string, service_name, "", "The service name to be launched");
 
 #ifdef __APPLE__
 using mozc::MacUtil;
@@ -61,37 +61,37 @@ int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
 #ifdef __APPLE__
-  if (mozc::GetFlag(FLAGS_label_for_suffix)) {
-    std::cout << MacUtil::GetLabelForSuffix(mozc::GetFlag(FLAGS_suffix))
+  if (absl::GetFlag(FLAGS_label_for_suffix)) {
+    std::cout << MacUtil::GetLabelForSuffix(absl::GetFlag(FLAGS_suffix))
               << std::endl;
   }
 
-  if (mozc::GetFlag(FLAGS_application_support_directory)) {
+  if (absl::GetFlag(FLAGS_application_support_directory)) {
     std::cout << MacUtil::GetApplicationSupportDirectory() << std::endl;
   }
 
-  if (mozc::GetFlag(FLAGS_logging_directory)) {
+  if (absl::GetFlag(FLAGS_logging_directory)) {
     std::cout << MacUtil::GetLoggingDirectory() << std::endl;
   }
 
-  if (mozc::GetFlag(FLAGS_os_version_string)) {
+  if (absl::GetFlag(FLAGS_os_version_string)) {
     std::cout << MacUtil::GetOSVersionString() << std::endl;
   }
 
-  if (mozc::GetFlag(FLAGS_server_directory)) {
+  if (absl::GetFlag(FLAGS_server_directory)) {
     std::cout << MacUtil::GetServerDirectory() << std::endl;
   }
 
-  if (mozc::GetFlag(FLAGS_serial_number)) {
+  if (absl::GetFlag(FLAGS_serial_number)) {
     std::cout << MacUtil::GetSerialNumber() << std::endl;
   }
 
-  if (mozc::GetFlag(FLAGS_start_launchd_service)) {
-    if (mozc::GetFlag(FLAGS_service_name).empty()) {
+  if (absl::GetFlag(FLAGS_start_launchd_service)) {
+    if (absl::GetFlag(FLAGS_service_name).empty()) {
       std::cout << "Specify the service name to be launched" << std::endl;
     } else {
       pid_t pid;
-      MacUtil::StartLaunchdService(mozc::GetFlag(FLAGS_service_name), &pid);
+      MacUtil::StartLaunchdService(absl::GetFlag(FLAGS_service_name), &pid);
       std::cout << "pid: " << pid << std::endl;
     }
   }
diff --git base/mmap.h base/mmap.h
index 028903589..93b52642b 100644
--- base/mmap.h
+++ base/mmap.h
@@ -55,7 +55,7 @@ class Mmap : public MmapSyncInterface {
   // - The storage is (usually) solid state thus page-in/out is expected to
   //   be faster.
   // On Linux, in the kernel version >= 2.6.9, user process can mlock. In older
-  // kernel, it fails if the process is running in user priviledge.
+  // kernel, it fails if the process is running in user privilege.
   // TODO(team): Check if mlock is really necessary for Mac.
   static bool IsMLockSupported();
   static int MaybeMLock(const void *addr, size_t len);
diff --git base/mmap_test.cc base/mmap_test.cc
index bdcea1a6f..160fb915b 100644
--- base/mmap_test.cc
+++ base/mmap_test.cc
@@ -34,17 +34,17 @@
 
 #include "base/file_stream.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/util.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace {
 
 TEST(MmapTest, MmapTest) {
   const std::string filename =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "test.db");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "test.db");
 
   const size_t kFileNameSize[] = {1, 100, 1024, 8192};
   for (int i = 0; i < arraysize(kFileNameSize); ++i) {
diff --git base/multifile_test.cc base/multifile_test.cc
index cb8b70d4a..c43c02eee 100644
--- base/multifile_test.cc
+++ base/multifile_test.cc
@@ -34,10 +34,10 @@
 
 #include "base/file_stream.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/util.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 
@@ -51,10 +51,10 @@ TEST(InputMultiFileTest, OpenNonexistentFilesTest) {
     EXPECT_FALSE(multfile.ReadLine(&line));
   }
 
-  // Signle path
+  // Single path
   {
     const std::string path = FileUtil::JoinPath(
-        mozc::GetFlag(FLAGS_test_tmpdir), "this_file_does_not_exist");
+        absl::GetFlag(FLAGS_test_tmpdir), "this_file_does_not_exist");
     InputMultiFile multfile(path);
     std::string line;
     EXPECT_FALSE(multfile.ReadLine(&line));
@@ -66,11 +66,11 @@ TEST(InputMultiFileTest, OpenNonexistentFilesTest) {
   {
     std::vector<std::string> filenames;
     filenames.push_back(
-        FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "these_files"));
+        FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "these_files"));
     filenames.push_back(
-        FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "do_not"));
+        FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "do_not"));
     filenames.push_back(
-        FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "exists"));
+        FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "exists"));
 
     std::string joined_path;
     Util::JoinStrings(filenames, ",", &joined_path);
@@ -83,9 +83,9 @@ TEST(InputMultiFileTest, OpenNonexistentFilesTest) {
 }
 
 TEST(InputMultiFileTest, ReadSingleFileTest) {
-  EXPECT_TRUE(FileUtil::DirectoryExists(mozc::GetFlag(FLAGS_test_tmpdir)));
+  EXPECT_TRUE(FileUtil::DirectoryExists(absl::GetFlag(FLAGS_test_tmpdir)));
   const std::string path =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "i_am_a_test_file");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "i_am_a_test_file");
 
   // Create a test file
   std::vector<std::string> expected_lines;
@@ -113,7 +113,7 @@ TEST(InputMultiFileTest, ReadSingleFileTest) {
 }
 
 TEST(InputMultiFileTest, ReadMultipleFilesTest) {
-  EXPECT_TRUE(FileUtil::DirectoryExists(mozc::GetFlag(FLAGS_test_tmpdir)));
+  EXPECT_TRUE(FileUtil::DirectoryExists(absl::GetFlag(FLAGS_test_tmpdir)));
 
   const int kNumFile = 3;
   const int kNumLinesPerFile = 10;
@@ -126,7 +126,7 @@ TEST(InputMultiFileTest, ReadMultipleFilesTest) {
     for (int fileno = 0; fileno < kNumFile; ++fileno) {
       std::string filename = Util::StringPrintf("testfile%d", fileno);
       std::string path =
-          FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), filename);
+          FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), filename);
       paths.push_back(path);
 
       OutputFileStream ofs(path.c_str());
diff --git base/number_util.cc base/number_util.cc
index b1f776978..fb3fe08b7 100644
--- base/number_util.cc
+++ base/number_util.cc
@@ -389,7 +389,7 @@ bool NumberUtil::ArabicToSeparatedArabic(absl::string_view input_num,
 namespace {
 
 // use default for wide Arabic, because half/full width for
-// normal number is learned by charactor form manager.
+// normal number is learned by character form manager.
 const NumberStringVariation kSingleDigitsVariations[] = {
     {kNumKanjiDigits, 10, "漢数字", nullptr, nullptr,
      NumberUtil::NumberString::NUMBER_KANJI_ARABIC},
diff --git base/number_util_test.cc base/number_util_test.cc
index 3582ade3a..3604aa0fa 100644
--- base/number_util_test.cc
+++ base/number_util_test.cc
@@ -583,7 +583,7 @@ TEST(NumberUtilTest, KanjiNumberToArabicNumber) {
 }
 
 TEST(NumberUtilTest, NormalizeNumbers) {
-  // An element has input, expected Kanji output, and exepcted Arabic output.
+  // An element has input, expected Kanji output, and expected Arabic output.
   const char *success_data[][3] = {
       {"一", "一", "1"},
       {"九", "九", "9"},
@@ -641,7 +641,7 @@ TEST(NumberUtilTest, NormalizeNumbers) {
     EXPECT_EQ(success_data[i][2], arabic_output);
   }
 
-  // An element has input, expected Kanji output, and exepcted Arabic output.
+  // An element has input, expected Kanji output, and expected Arabic output.
   const char *success_notrim_data[][3] = {
       {"０１２", "〇一二", "012"},
       {"０00", "〇〇〇", "000"},
diff --git base/password_manager.cc base/password_manager.cc
index 9e35f23c9..0ca8194b7 100644
--- base/password_manager.cc
+++ base/password_manager.cc
@@ -135,7 +135,7 @@ bool LoadPassword(std::string *password) {
     return false;
   }
 
-  // Seems that the size of DPAPI-encrypted-mesage
+  // Seems that the size of DPAPI-encrypted-message
   // becomes bigger than the original message.
   // Typical file size is 32 * 5 = 160byte.
   // We just set the maximum file size to be 4096byte just in case.
diff --git base/password_manager_main.cc base/password_manager_main.cc
index 41fa60428..6af134eb6 100644
--- base/password_manager_main.cc
+++ base/password_manager_main.cc
@@ -27,11 +27,11 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/password_manager.h"
 #include "base/util.h"
+#include "absl/flags/flag.h"
 
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
diff --git base/password_manager_test.cc base/password_manager_test.cc
index b9776d00a..35ba43725 100644
--- base/password_manager_test.cc
+++ base/password_manager_test.cc
@@ -29,14 +29,14 @@
 
 #include "base/password_manager.h"
 
-#include "base/flags.h"
 #include "base/system_util.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 TEST(PasswordManager, PasswordManagerTest) {
-  SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+  SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
 
   std::string password1, password2;
   EXPECT_TRUE(PasswordManager::InitPassword());
diff --git base/process.h base/process.h
index ca906f39e..dc3ffe744 100644
--- base/process.h
+++ base/process.h
@@ -65,7 +65,7 @@ class Process {
   static bool WaitProcess(size_t pid, int timeout);
 
   // Returns true if a process having |pid| is still alive.
-  // if the the current thread has no permission to get the status or
+  // if the current thread has no permission to get the status or
   // operation failed in system call, it returns |default_result|.
   // TODO(all):
   // Note that there is the case where the specified thread/process has already
diff --git base/process_main.cc base/process_main.cc
index 7b2405732..dfb2111b5 100644
--- base/process_main.cc
+++ base/process_main.cc
@@ -29,24 +29,24 @@
 
 #include <string>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/process.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, open_browser, "", "URL");
-MOZC_FLAG(string, spawn_process, "", "path");
+ABSL_FLAG(std::string, open_browser, "", "URL");
+ABSL_FLAG(std::string, spawn_process, "", "path");
 
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
-  if (!mozc::GetFlag(FLAGS_open_browser).empty()) {
-    if (!mozc::Process::OpenBrowser(mozc::GetFlag(FLAGS_open_browser))) {
-      LOG(INFO) << "Failed to open: " << mozc::GetFlag(FLAGS_open_browser);
+  if (!absl::GetFlag(FLAGS_open_browser).empty()) {
+    if (!mozc::Process::OpenBrowser(absl::GetFlag(FLAGS_open_browser))) {
+      LOG(INFO) << "Failed to open: " << absl::GetFlag(FLAGS_open_browser);
     }
   }
-  if (!mozc::GetFlag(FLAGS_spawn_process).empty()) {
-    if (!mozc::Process::SpawnProcess(mozc::GetFlag(FLAGS_spawn_process), "")) {
-      LOG(INFO) << "Failed to spawn: " << mozc::GetFlag(FLAGS_spawn_process);
+  if (!absl::GetFlag(FLAGS_spawn_process).empty()) {
+    if (!mozc::Process::SpawnProcess(absl::GetFlag(FLAGS_spawn_process), "")) {
+      LOG(INFO) << "Failed to spawn: " << absl::GetFlag(FLAGS_spawn_process);
     }
   }
   return 0;
diff --git base/process_mutex.h base/process_mutex.h
index 68cf1ed4f..b8e411ea1 100644
--- base/process_mutex.h
+++ base/process_mutex.h
@@ -50,7 +50,7 @@
 // }
 //
 // foo.Lock();
-// /* process named "foo" is never instatiated inside this block */
+// /* process named "foo" is never instantiated inside this block */
 // foo.Unlock();
 
 namespace mozc {
diff --git base/process_mutex_main.cc base/process_mutex_main.cc
index 05bc2f46c..4b44b0111 100644
--- base/process_mutex_main.cc
+++ base/process_mutex_main.cc
@@ -34,28 +34,28 @@
 #endif  // OS_WIN
 #include <string>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(int32, sleep_time, 30, "sleep 30 sec");
-MOZC_FLAG(string, name, "named_event_test", "name for named event");
+ABSL_FLAG(int32, sleep_time, 30, "sleep 30 sec");
+ABSL_FLAG(std::string, name, "named_event_test", "name for named event");
 
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
-  mozc::ProcessMutex mutex(mozc::GetFlag(FLAGS_name).c_str());
+  mozc::ProcessMutex mutex(absl::GetFlag(FLAGS_name).c_str());
 
   if (!mutex.Lock()) {
-    LOG(INFO) << "Process " << mozc::GetFlag(FLAGS_name)
+    LOG(INFO) << "Process " << absl::GetFlag(FLAGS_name)
               << " is already running";
     return -1;
   }
 
 #ifdef OS_WIN
-  ::Sleep(mozc::GetFlag(FLAGS_sleep_time) * 1000);
+  ::Sleep(absl::GetFlag(FLAGS_sleep_time) * 1000);
 #else
-  ::sleep(mozc::GetFlag(FLAGS_sleep_time));
+  ::sleep(absl::GetFlag(FLAGS_sleep_time));
 #endif
 
   mutex.UnLock();
diff --git base/process_mutex_test.cc base/process_mutex_test.cc
index d3050590f..b29af1c21 100644
--- base/process_mutex_test.cc
+++ base/process_mutex_test.cc
@@ -36,12 +36,12 @@
 #endif  // OS_WIN
 
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/system_util.h"
 #include "base/util.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace {
@@ -51,7 +51,7 @@ class ProcessMutexTest : public testing::Test {
  protected:
   void SetUp() override {
     original_user_profile_dir_ = SystemUtil::GetUserProfileDirectory();
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   }
 
   void TearDown() override {
diff --git base/run_level_main.cc base/run_level_main.cc
index c91f35b91..a12be8d92 100644
--- base/run_level_main.cc
+++ base/run_level_main.cc
@@ -31,12 +31,12 @@
 #include <string>
 #include <vector>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/run_level.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(bool, server, false, "server mode");
-MOZC_FLAG(bool, client, false, "client mode");
+ABSL_FLAG(bool, server, false, "server mode");
+ABSL_FLAG(bool, client, false, "client mode");
 
 // This is a simple command line tool
 // too check RunLevel class
@@ -45,9 +45,9 @@ int main(int argc, char **argv) {
 
   mozc::RunLevel::RequestType type = mozc::RunLevel::SERVER;
 
-  if (mozc::GetFlag(FLAGS_client)) {
+  if (absl::GetFlag(FLAGS_client)) {
     type = mozc::RunLevel::CLIENT;
-  } else if (mozc::GetFlag(FLAGS_server)) {
+  } else if (absl::GetFlag(FLAGS_server)) {
     type = mozc::RunLevel::SERVER;
   }
 
diff --git base/scheduler.h base/scheduler.h
index 75160258c..ec25a26e3 100644
--- base/scheduler.h
+++ base/scheduler.h
@@ -30,7 +30,7 @@
 // Scheduler is a timer, call registered callback at a given interval.
 // Scheduler has following features.
 //  1. Backoff when the registered callback returns false.
-//    - When the backoff is occured, next try will be after 2 * interval msec.
+//    - When the backoff is occurred, next try will be after 2 * interval msec.
 //    - Interval will be doubled as long as callback returns false, but
 //      will not exceed max_interval.
 //  2. Randomised delayed start to reduce server traffic peak.
diff --git base/singleton_test.cc base/singleton_test.cc
index dea826ab2..c3b7e2031 100644
--- base/singleton_test.cc
+++ base/singleton_test.cc
@@ -81,8 +81,8 @@ TEST(SingletonTest, BasicTest) {
 }
 
 TEST(SingletonTest, ThreadTest) {
-  // call Singelton::get() at the same time from
-  // different threds. Make sure that get() returns
+  // call Singleton::get() at the same time from
+  // different threads. Make sure that get() returns
   // the same instance
 
   g_counter = 0;
diff --git base/stopwatch_main.cc base/stopwatch_main.cc
index 4d52a8350..3a656f8c6 100644
--- base/stopwatch_main.cc
+++ base/stopwatch_main.cc
@@ -30,19 +30,19 @@
 #include <iostream>
 #include <string>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/stopwatch.h"
 #include "base/util.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(int32, sleep_time, 1000, "sleep time");
+ABSL_FLAG(int32, sleep_time, 1000, "sleep time");
 
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
   mozc::Stopwatch stopwatch;
   stopwatch.Start();
-  mozc::Util::Sleep(mozc::GetFlag(FLAGS_sleep_time));
+  mozc::Util::Sleep(absl::GetFlag(FLAGS_sleep_time));
   stopwatch.Stop();
   std::cout << stopwatch.GetElapsedMicroseconds() << std::endl;
 
diff --git base/unverified_aes256.h base/unverified_aes256.h
index e431bf6ea..ffae1e302 100644
--- base/unverified_aes256.h
+++ base/unverified_aes256.h
@@ -35,7 +35,7 @@
 namespace mozc {
 namespace internal {
 
-// Note that this implemenation is kept just for the backward compatibility
+// Note that this implementation is kept just for the backward compatibility
 // so that we can read previously obfuscated data.
 // !!! Not FIPS-certified.
 // !!! Performance optimization is not well considered.
diff --git base/unverified_sha1.h base/unverified_sha1.h
index 988fd1269..5b3a76f62 100644
--- base/unverified_sha1.h
+++ base/unverified_sha1.h
@@ -36,7 +36,7 @@
 namespace mozc {
 namespace internal {
 
-// Note that this implemenation is kept just for the backward compatibility
+// Note that this implementation is kept just for the backward compatibility
 // so that we can read previously obfuscated data.
 // !!! Not FIPS-certified.
 // !!! Performance optimization is not well considered.
diff --git base/win_sandbox.cc base/win_sandbox.cc
index 140ef6baa..fec250bb8 100644
--- base/win_sandbox.cc
+++ base/win_sandbox.cc
@@ -257,7 +257,7 @@ std::wstring WinSandbox::GetSDDL(ObjectSecurityType shareble_object_type,
                                  bool is_windows_8_or_later) {
   // See
   // http://social.msdn.microsoft.com/Forums/en-US/windowssecurity/thread/e92502b1-0b9f-4e02-9d72-e4e47e924a8f/
-  // for how to acess named objects from an AppContainer.
+  // for how to access named objects from an AppContainer.
 
   std::wstring dacl;
   std::wstring sacl;
@@ -1393,12 +1393,12 @@ bool WinSandbox::EnsureAllApplicationPackagesPermisssion(
   // Check if the desired ACE is already specified or not.
   for (UINT i = 0; i < dacl.GetAceCount(); ++i) {
     CSid ace_sid;
-    ACCESS_MASK acess_mask = 0;
+    ACCESS_MASK access_mask = 0;
     BYTE ace_type = 0;
-    dacl.GetAclEntry(i, &ace_sid, &acess_mask, &ace_type);
+    dacl.GetAclEntry(i, &ace_sid, &access_mask, &ace_type);
     if (ace_sid == all_application_packages &&
         ace_type == ACCESS_ALLOWED_ACE_TYPE &&
-        (acess_mask & kDesiredMask) == kDesiredMask) {
+        (access_mask & kDesiredMask) == kDesiredMask) {
       // This is the desired ACE.  There is nothing to do.
       return true;
     }
diff --git build_defs.bzl build_defs.bzl
index ccf4e6eae..d0d3fc57f 100644
--- build_defs.bzl
+++ build_defs.bzl
@@ -35,6 +35,8 @@
 load("//tools/build_defs:build_cleaner.bzl", "register_extension_info")
 load("//tools/build_defs:stubs.bzl", "pytype_strict_binary", "pytype_strict_library")
 load("//tools/build_rules/android_cc_test:def.bzl", "android_cc_test")
+load("//:config.bzl", "BRANDING", "MACOS_BUNDLE_ID_PREFIX", "MACOS_MIN_OS_VER")
+load("@build_bazel_rules_apple//apple:macos.bzl", "macos_application")
 
 def cc_library_mozc(deps = [], **kwargs):
     """
@@ -80,12 +82,12 @@ def cc_test_mozc(name, tags = [], deps = [], **kwargs):
     if "no_android" not in tags:
         android_cc_test(
             name = name + "_android",
+            cc_test_name = name,
+            requires_full_emulation = requires_full_emulation,
             # "manual" prevents this target triggered by a wild card.
             # So that "blaze test ..." does not contain this target.
             # Otherwise it is too slow.
             tags = ["manual", "notap"],
-            cc_test_name = name,
-            requires_full_emulation = requires_full_emulation,
         )
 
 register_extension_info(
@@ -130,16 +132,45 @@ register_extension_info(
     label_regex_for_dep = "{extension_name}",
 )
 
-def objc_library_mozc(name, srcs = [], hdrs = [], deps = [], sdk_frameworks = [], **kwargs):
+def info_plist_mozc(name, srcs = [], outs = []):
+    native.genrule(
+        name = name,
+        srcs = srcs + ["//base:mozc_version_txt"],
+        outs = outs,
+        cmd = ("$(location //build_tools:tweak_info_plist)" +
+               " --output $@" +
+               " --input $(location " + srcs[0] + ")" +
+               " --version_file $(location //base:mozc_version_txt)" +
+               " --branding " + BRANDING),
+        exec_tools = ["//build_tools:tweak_info_plist"],
+    )
+
+def objc_library_mozc(name, srcs = [], hdrs = [], deps = [], proto_deps = [], sdk_frameworks = [], **kwargs):
+    # Because proto_library cannot be in deps of objc_library,
+    # cc_library as a wrapper is necessary as a workaround.
+    proto_deps_name = name + "_proto_deps"
+    native.cc_library(
+        name = proto_deps_name,
+        deps = proto_deps,
+    )
     native.objc_library(
         name = name,
         srcs = srcs,
         hdrs = hdrs,
-        deps = deps + ["//:macro"],
+        deps = deps + ["//:macro", proto_deps_name],
         sdk_frameworks = sdk_frameworks,
         **kwargs
     )
 
+def macos_application_mozc(name, bundle_name, bundle_id = None, **kwargs):
+    macos_application(
+        name = name,
+        bundle_id = bundle_id or (MACOS_BUNDLE_ID_PREFIX + "." + bundle_name),
+        bundle_name = bundle_name,
+        minimum_os_version = MACOS_MIN_OS_VER,
+        **kwargs
+    )
+
 def _get_value(args):
     for arg in args:
         if arg != None:
@@ -158,7 +189,8 @@ def select_mozc(
         oss_android = None,
         oss_linux = None,
         oss_macos = None,
-        wasm = None):
+        wasm = None,
+        windows = None):
     """select wrapper for target os selection.
 
     The priority of value checking:
@@ -181,6 +213,7 @@ def select_mozc(
       oss_linux: value for OSS Linux build.
       oss_macos: value for OSS macOS build.
       wasm: value for wasm build.
+      windows: value for Windows build. (placeholder)
 
     Returns:
       Generated select statement.
@@ -189,8 +222,9 @@ def select_mozc(
         "//tools/cc_target_os:android": _get_value([android, client, default]),
         "//tools/cc_target_os:apple": _get_value([ios, client, default]),
         "//tools/cc_target_os:chromiumos": _get_value([chromiumos, client, default]),
-        "//tools/cc_target_os:wasm": _get_value([wasm, client, default]),
         "//tools/cc_target_os:darwin": _get_value([macos, ios, client, default]),
+        "//tools/cc_target_os:wasm": _get_value([wasm, client, default]),
+        "//tools/cc_target_os:windows": _get_value([windows, client, default]),
         "//tools/cc_target_os:linux": _get_value([linux, client, default]),
         "//tools/cc_target_os:oss_android": _get_value([oss_android, oss, android, client, default]),
         "//tools/cc_target_os:oss_linux": _get_value([oss_linux, oss, linux, client, default]),
diff --git build_tools/copy_dll_and_symbol.py build_tools/copy_dll_and_symbol.py
index 0f871190f..e0177c2b0 100644
--- build_tools/copy_dll_and_symbol.py
+++ build_tools/copy_dll_and_symbol.py
@@ -82,12 +82,13 @@ def _GetLastModifiedTime(filepath):
     Args:
       filepath: A string which represents the filename to be checked.
 
-      Returns:
-        A Datetime object which represents the last modified time of the
-        specified filename. If the file does not exist, returns epoch time.
+    Returns:
+      A Datetime object which represents the last modified time of the
+      specified filename. If the file does not exist, returns epoch time +1 day.
     """
     if not os.path.isfile(filepath):
-      return datetime.datetime.fromtimestamp(0)
+      # The epoch time doesn't work in some timezones. 86400 = 24 * 60 * 60.
+      return datetime.datetime.fromtimestamp(86400)
     return datetime.datetime.fromtimestamp(os.path.getmtime(filepath))
 
   target_file_mtime = _GetLastModifiedTime(target_file_abspath)
diff --git build_tools/mozc_win32_resource_template.rc build_tools/mozc_win32_resource_template.rc
index 72f401f66..7776912d8 100644
Binary files build_tools/mozc_win32_resource_template.rc and build_tools/mozc_win32_resource_template.rc differ
diff --git client/BUILD client/BUILD
index 099654818..840880f62 100644
--- client/BUILD
+++ client/BUILD
@@ -127,7 +127,6 @@ cc_binary_mozc(
     deps = [
         ":client",
         "//base",
-        "//base:flags",
         "//base:init_mozc",
         "//base:logging",
         "//base:process",
@@ -142,7 +141,6 @@ cc_binary_mozc(
         ":client",
         "//base",
         "//base:file_stream",
-        "//base:flags",
         "//base:init_mozc",
         "//base:logging",
         "//base:port",
@@ -162,7 +160,6 @@ cc_binary_mozc(
         "//base",
         "//base:file_stream",
         "//base:file_util",
-        "//base:flags",
         "//base:init_mozc",
         "//base:logging",
         "//base:port",
@@ -185,7 +182,6 @@ cc_binary_mozc(
         ":client",
         "//base",
         "//base:file_stream",
-        "//base:flags",
         "//base:init_mozc",
         "//base:logging",
         "//base:port",
@@ -206,9 +202,9 @@ cc_binary_mozc(
     deps = [
         ":client",
         "//base",
-        "//base:flags",
         "//base:init_mozc",
         "//base:logging",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -237,7 +233,6 @@ cc_binary_mozc(
         ":client",
         "//base",
         "//base:file_stream",
-        "//base:flags",
         "//base:init_mozc",
         "//base:logging",
         "//base:multifile",
diff --git client/client.h client/client.h
index 3c7224489..0d4d52aed 100644
--- client/client.h
+++ client/client.h
@@ -51,7 +51,7 @@ class Config;
 
 namespace client {
 
-// default ServerLauncher implemntation.
+// default ServerLauncher implementation.
 // This class uses fork&exec (linux/mac) and CreateProcess() (Windows)
 // to launch server process
 class ServerLauncher : public ServerLauncherInterface {
@@ -177,8 +177,9 @@ class Client : public ClientInterface {
                            const std::string &label) const;
 
   // Start server:
-  // return true if server is launched sucessfully or server is already running.
-  // return false if server cannot be launched.
+  // * Return true if server is launched successfully or server is already
+  //   running.
+  // * Return false if server cannot be launched.
   // If server_program is empty, which is default setting, the path to
   // GoogleJapaneseInputConverter is determined automatically.
   // Windows: "C:\Program Files\Google\Google Japanese Input\"
diff --git client/client_interface.h client/client_interface.h
index 14f1313c2..8a1ea88bc 100644
--- client/client_interface.h
+++ client/client_interface.h
@@ -73,7 +73,7 @@ class ServerLauncherInterface {
   // Wait server until it terminates
   virtual bool WaitServer(uint32 pid) = 0;
 
-  // called when fatal error occured.
+  // called when fatal error occurred.
   virtual void OnFatal(ServerErrorType type) = 0;
 
   // set the full path of server program.
@@ -121,7 +121,7 @@ class ClientInterface {
   // Checks protocol/product version.
   // If a  new version is avaialable, restart the server.
   // return true the server is available.
-  // return false some error happend during the server restart.
+  // return false some error happened during the server restart.
   // This method calls EnsureConnection automatically.
   virtual bool CheckVersionOrRestartServer() = 0;
 
@@ -181,7 +181,7 @@ class ClientInterface {
   // Cleanup un-used sessions
   virtual bool Cleanup() = 0;
 
-  // Resets internal state (changs the state to be SERVER_UNKNWON)
+  // Resets internal state (changs the state to be SERVER_UNKNOWN)
   virtual void Reset() = 0;
 
   // Returns true if server is alive.
@@ -200,7 +200,7 @@ class ClientInterface {
   virtual void set_timeout(int timeout) = 0;
 
   // Sets restricted mode.
-  // server is launched inside restricted enviroment.
+  // server is launched inside restricted environment.
   virtual void set_restricted(bool restricted) = 0;
 
   // Sets server program path.
diff --git client/client_performance_test_main.cc client/client_performance_test_main.cc
index defdb2eda..3a377628f 100644
--- client/client_performance_test_main.cc
+++ client/client_performance_test_main.cc
@@ -35,7 +35,6 @@
 #include <vector>
 
 #include "base/file_stream.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/port.h"
@@ -48,8 +47,8 @@
 #include "session/random_keyevents_generator.h"
 #include "absl/flags/flag.h"
 
-MOZC_FLAG(string, server_path, "", "specify server path");
-MOZC_FLAG(string, log_path, "", "specify log output file path");
+ABSL_FLAG(std::string, server_path, "", "specify server path");
+ABSL_FLAG(std::string, log_path, "", "specify log output file path");
 
 namespace mozc {
 namespace {
@@ -100,8 +99,8 @@ class TestScenarioInterface {
   virtual void Run(Result *result) = 0;
 
   TestScenarioInterface() {
-    if (!mozc::GetFlag(FLAGS_server_path).empty()) {
-      client_.set_server_program(mozc::GetFlag(FLAGS_server_path));
+    if (!absl::GetFlag(FLAGS_server_path).empty()) {
+      client_.set_server_program(absl::GetFlag(FLAGS_server_path));
     }
     CHECK(client_.IsValidRunLevel()) << "IsValidRunLevel failed";
     CHECK(client_.EnsureSession()) << "EnsureSession failed";
@@ -378,8 +377,8 @@ int main(int argc, char **argv) {
   CHECK_EQ(results.size(), tests.size());
 
   std::ostream *ofs = &std::cout;
-  if (!mozc::GetFlag(FLAGS_log_path).empty()) {
-    ofs = new mozc::OutputFileStream(mozc::GetFlag(FLAGS_log_path).c_str());
+  if (!absl::GetFlag(FLAGS_log_path).empty()) {
+    ofs = new mozc::OutputFileStream(absl::GetFlag(FLAGS_log_path).c_str());
   }
 
   // TODO(taku): generate histogram with ChartAPI
diff --git client/client_quality_test_main.cc client/client_quality_test_main.cc
index d43d203f9..a88baac88 100644
--- client/client_quality_test_main.cc
+++ client/client_quality_test_main.cc
@@ -34,7 +34,6 @@
 #include <vector>
 
 #include "base/file_stream.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/multifile.h"
@@ -43,15 +42,15 @@
 #include "client/client.h"
 #include "evaluation/scorer.h"
 #include "protocol/commands.pb.h"
+#include "absl/flags/flag.h"
 
 // Test data automatically generated by gen_client_quality_test_data.py
 // TestCase test_cases[] is defined.
 #include "client/client_quality_test_data.inc"
-#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, server_path, "", "specify server path");
-MOZC_FLAG(string, log_path, "", "specify log output file path");
-MOZC_FLAG(int32, max_case_for_source, 500,
+ABSL_FLAG(std::string, server_path, "", "specify server path");
+ABSL_FLAG(std::string, log_path, "", "specify log output file path");
+ABSL_FLAG(int32, max_case_for_source, 500,
           "specify max test case number for each test sources");
 
 namespace mozc {
@@ -203,8 +202,8 @@ int main(int argc, char* argv[]) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
   mozc::client::Client client;
-  if (!mozc::GetFlag(FLAGS_server_path).empty()) {
-    client.set_server_program(mozc::GetFlag(FLAGS_server_path));
+  if (!absl::GetFlag(FLAGS_server_path).empty()) {
+    client.set_server_program(absl::GetFlag(FLAGS_server_path));
   }
 
   CHECK(client.IsValidRunLevel()) << "IsValidRunLevel failed";
@@ -222,7 +221,7 @@ int main(int argc, char* argv[]) {
     if (scores.find(source) == scores.end()) {
       scores[source] = std::vector<double>();
     }
-    if (scores[source].size() >= mozc::GetFlag(FLAGS_max_case_for_source)) {
+    if (scores[source].size() >= absl::GetFlag(FLAGS_max_case_for_source)) {
       continue;
     }
 
@@ -248,8 +247,8 @@ int main(int argc, char* argv[]) {
   }
 
   std::ostream* ofs = &std::cout;
-  if (!mozc::GetFlag(FLAGS_log_path).empty()) {
-    ofs = new mozc::OutputFileStream(mozc::GetFlag(FLAGS_log_path).c_str());
+  if (!absl::GetFlag(FLAGS_log_path).empty()) {
+    ofs = new mozc::OutputFileStream(absl::GetFlag(FLAGS_log_path).c_str());
   }
 
   // Average the scores
diff --git client/client_scenario_test_main.cc client/client_scenario_test_main.cc
index 584dbb985..acdb700fe 100644
--- client/client_scenario_test_main.cc
+++ client/client_scenario_test_main.cc
@@ -39,7 +39,6 @@
 
 #include "base/file_stream.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/port.h"
@@ -54,13 +53,13 @@
 #include "absl/memory/memory.h"
 #include "absl/strings/match.h"
 
-MOZC_FLAG(string, input, "", "Input file");
-MOZC_FLAG(int32, key_duration, 10, "Key duration (msec)");
-MOZC_FLAG(string, profile_dir, "", "Profile dir");
-MOZC_FLAG(bool, sentence_mode, false, "Use input as sentences");
-MOZC_FLAG(string, server_path, "", "Specify server path");
-MOZC_FLAG(bool, test_renderer, false, "Test renderer");
-MOZC_FLAG(bool, test_testsendkey, true, "Test TestSendKey");
+ABSL_FLAG(std::string, input, "", "Input file");
+ABSL_FLAG(int32, key_duration, 10, "Key duration (msec)");
+ABSL_FLAG(std::string, profile_dir, "", "Profile dir");
+ABSL_FLAG(bool, sentence_mode, false, "Use input as sentences");
+ABSL_FLAG(std::string, server_path, "", "Specify server path");
+ABSL_FLAG(bool, test_renderer, false, "Test renderer");
+ABSL_FLAG(bool, test_testsendkey, true, "Test TestSendKey");
 
 namespace mozc {
 namespace {
@@ -97,8 +96,8 @@ bool ReadKeys(std::istream *input, std::vector<commands::KeyEvent> *keys,
 
 int Loop(std::istream *input) {
   mozc::client::Client client;
-  if (!mozc::GetFlag(FLAGS_server_path).empty()) {
-    client.set_server_program(mozc::GetFlag(FLAGS_server_path));
+  if (!absl::GetFlag(FLAGS_server_path).empty()) {
+    client.set_server_program(absl::GetFlag(FLAGS_server_path));
   }
 
   CHECK(client.IsValidRunLevel()) << "IsValidRunLevel failed";
@@ -108,7 +107,7 @@ int Loop(std::istream *input) {
   std::unique_ptr<mozc::renderer::RendererClient> renderer_client;
   mozc::commands::RendererCommand renderer_command;
 
-  if (mozc::GetFlag(FLAGS_test_renderer)) {
+  if (absl::GetFlag(FLAGS_test_renderer)) {
 #ifdef OS_WIN
     renderer_command.mutable_application_info()->set_process_id(
         ::GetCurrentProcessId());
@@ -139,9 +138,9 @@ int Loop(std::istream *input) {
   while (ReadKeys(input, &keys, &answer)) {
     CHECK(client.NoOperation()) << "Server is not responding";
     for (size_t i = 0; i < keys.size(); ++i) {
-      Util::Sleep(mozc::GetFlag(FLAGS_key_duration));
+      Util::Sleep(absl::GetFlag(FLAGS_key_duration));
 
-      if (mozc::GetFlag(FLAGS_test_testsendkey)) {
+      if (absl::GetFlag(FLAGS_test_testsendkey)) {
         VLOG(2) << "Sending to Server: " << keys[i].DebugString();
         client.TestSendKey(keys[i], &output);
         VLOG(2) << "Output of TestSendKey: " << output.DebugString();
@@ -175,20 +174,20 @@ int Loop(std::istream *input) {
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
-  if (!mozc::GetFlag(FLAGS_profile_dir).empty()) {
-    mozc::FileUtil::CreateDirectory(mozc::GetFlag(FLAGS_profile_dir));
-    mozc::SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_profile_dir));
+  if (!absl::GetFlag(FLAGS_profile_dir).empty()) {
+    mozc::FileUtil::CreateDirectory(absl::GetFlag(FLAGS_profile_dir));
+    mozc::SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_profile_dir));
   }
 
   std::unique_ptr<mozc::InputFileStream> input_file;
   std::istream *input = nullptr;
 
-  if (!mozc::GetFlag(FLAGS_input).empty()) {
+  if (!absl::GetFlag(FLAGS_input).empty()) {
     // Batch mode loading the input file.
     input_file = absl::make_unique<mozc::InputFileStream>(
-        mozc::GetFlag(FLAGS_input).c_str());
+        absl::GetFlag(FLAGS_input).c_str());
     if (input_file->fail()) {
-      LOG(ERROR) << "File not opened: " << mozc::GetFlag(FLAGS_input);
+      LOG(ERROR) << "File not opened: " << absl::GetFlag(FLAGS_input);
       return 1;
     }
     input = input_file.get();
diff --git client/client_stress_test_main.cc client/client_stress_test_main.cc
index a7e74c134..6b3d892a8 100644
--- client/client_stress_test_main.cc
+++ client/client_stress_test_main.cc
@@ -41,7 +41,6 @@
 #include <memory>
 
 #include "base/file_stream.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/port.h"
@@ -55,21 +54,21 @@
 // 1. multi-thread testing
 // 2. change/config the senario
 
-MOZC_FLAG(int32, max_keyevents, 100000,
+ABSL_FLAG(int32, max_keyevents, 100000,
           "test at most |max_keyevents| key sequences");
-MOZC_FLAG(string, server_path, "", "specify server path");
-MOZC_FLAG(int32, key_duration, 10, "key duration (msec)");
-MOZC_FLAG(bool, test_renderer, false, "test renderer");
-MOZC_FLAG(bool, test_testsendkey, true, "test TestSendKey");
+ABSL_FLAG(std::string, server_path, "", "specify server path");
+ABSL_FLAG(int32, key_duration, 10, "key duration (msec)");
+ABSL_FLAG(bool, test_renderer, false, "test renderer");
+ABSL_FLAG(bool, test_testsendkey, true, "test TestSendKey");
 
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
-  mozc::SetFlag(&FLAGS_logtostderr, true);
+  absl::SetFlag(&FLAGS_logtostderr, true);
 
   mozc::client::Client client;
-  if (!mozc::GetFlag(FLAGS_server_path).empty()) {
-    client.set_server_program(mozc::GetFlag(FLAGS_server_path));
+  if (!absl::GetFlag(FLAGS_server_path).empty()) {
+    client.set_server_program(absl::GetFlag(FLAGS_server_path));
   }
 
   CHECK(client.IsValidRunLevel()) << "IsValidRunLevel failed";
@@ -79,7 +78,7 @@ int main(int argc, char **argv) {
   std::unique_ptr<mozc::renderer::RendererClient> renderer_client;
   mozc::commands::RendererCommand renderer_command;
 
-  if (mozc::GetFlag(FLAGS_test_renderer)) {
+  if (absl::GetFlag(FLAGS_test_renderer)) {
 #ifdef OS_WIN
     renderer_command.mutable_application_info()->set_process_id(
         ::GetCurrentProcessId());
@@ -111,17 +110,17 @@ int main(int argc, char **argv) {
     mozc::session::RandomKeyEventsGenerator::GenerateSequence(&keys);
     CHECK(client.NoOperation()) << "Server is not responding";
     for (size_t i = 0; i < keys.size(); ++i) {
-      mozc::Util::Sleep(mozc::GetFlag(FLAGS_key_duration));
+      mozc::Util::Sleep(absl::GetFlag(FLAGS_key_duration));
       keyevents_size++;
       if (keyevents_size % 100 == 0) {
         std::cout << keyevents_size << " key events finished" << std::endl;
       }
-      if (mozc::GetFlag(FLAGS_max_keyevents) < keyevents_size) {
+      if (absl::GetFlag(FLAGS_max_keyevents) < keyevents_size) {
         std::cout << "key events reached to "
-                  << mozc::GetFlag(FLAGS_max_keyevents) << std::endl;
+                  << absl::GetFlag(FLAGS_max_keyevents) << std::endl;
         return 0;
       }
-      if (mozc::GetFlag(FLAGS_test_testsendkey)) {
+      if (absl::GetFlag(FLAGS_test_testsendkey)) {
         VLOG(2) << "Sending to Server: " << keys[i].DebugString();
         client.TestSendKey(keys[i], &output);
         VLOG(2) << "Output of TestSendKey: " << output.DebugString();
diff --git client/ping_server_main.cc client/ping_server_main.cc
index 879191b73..261a2daf6 100644
--- client/ping_server_main.cc
+++ client/ping_server_main.cc
@@ -29,10 +29,10 @@
 
 #include <iostream>  // NOLINT
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "client/client.h"
+#include "absl/flags/flag.h"
 
 // Simple command line tool to ping mozc server
 int main(int argc, char **argv) {
diff --git client/server_launcher.cc client/server_launcher.cc
index 24e37cd8c..c201c5d0a 100644
--- client/server_launcher.cc
+++ client/server_launcher.cc
@@ -132,7 +132,7 @@ bool ServerLauncher::StartServer(ClientInterface *client) {
 #endif
 
 #ifdef DEBUG
-  // In oreder to test the Session treatment (timeout/size constratins),
+  // In order to test the Session treatment (timeout/size constratins),
   // Server flags can be configurable on DEBUG build
   if (!arg.empty()) {
     arg += " ";
diff --git client/server_launcher_main.cc client/server_launcher_main.cc
index 67e045bf7..f3381f500 100644
--- client/server_launcher_main.cc
+++ client/server_launcher_main.cc
@@ -29,20 +29,19 @@
 
 #include <iostream>  // NOLINT
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "client/client.h"
 #include "absl/flags/flag.h"
 
-MOZC_FLAG(bool, shutdown, false, "shutdown server if mozc_server is running");
+ABSL_FLAG(bool, shutdown, false, "shutdown server if mozc_server is running");
 
 // simple command line tool to launch mozc server
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
   mozc::client::Client client;
 
-  if (mozc::GetFlag(FLAGS_shutdown)) {
+  if (absl::GetFlag(FLAGS_shutdown)) {
     client.Shutdown();
   }
 
diff --git composer/BUILD composer/BUILD
index c3a74b721..7d27f0780 100644
--- composer/BUILD
+++ composer/BUILD
@@ -49,7 +49,6 @@ cc_library_mozc(
         ":table",
         ":type_corrected_query",
         "//base",
-        "//base:flags",
         "//base:logging",
         "//base:port",
         "//base:util",
@@ -66,6 +65,7 @@ cc_library_mozc(
         "//protocol:config_proto",
         "//testing:gunit_prod",
         "//transliteration",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -145,12 +145,12 @@ cc_binary_mozc(
         ":composition_interface",
         ":table",
         "//base",
-        "//base:flags",
         "//base:init_mozc",
         "//base/protobuf",
         "//protocol:commands_proto",
         "//protocol:config_proto",
         "//transliteration",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
diff --git composer/composer.cc composer/composer.cc
index 5c8beb304..077874526 100644
--- composer/composer.cc
+++ composer/composer.cc
@@ -31,7 +31,6 @@
 
 #include "composer/composer.h"
 
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/util.h"
 #include "composer/internal/composition.h"
@@ -46,11 +45,12 @@
 #include "config/config_handler.h"
 #include "protocol/commands.pb.h"
 #include "protocol/config.pb.h"
+#include "absl/flags/flag.h"
 
 // Use flags instead of constant for performance evaluation.
-MOZC_FLAG(uint64, max_typing_correction_query_candidates, 40,
+ABSL_FLAG(uint64, max_typing_correction_query_candidates, 40,
           "Maximum # of typing correction query temporary candidates.");
-MOZC_FLAG(uint64, max_typing_correction_query_results, 8,
+ABSL_FLAG(uint64, max_typing_correction_query_results, 8,
           "Maximum # of typing correction query results.");
 
 namespace mozc {
@@ -208,8 +208,8 @@ Composer::Composer(const Table *table, const commands::Request *request,
       shifted_sequence_count_(0),
       composition_(new Composition(table)),
       typing_corrector_(
-          table, mozc::GetFlag(FLAGS_max_typing_correction_query_candidates),
-          mozc::GetFlag(FLAGS_max_typing_correction_query_results)),
+          table, absl::GetFlag(FLAGS_max_typing_correction_query_candidates),
+          absl::GetFlag(FLAGS_max_typing_correction_query_results)),
       max_length_(kMaxPreeditLength),
       request_(request),
       config_(config) {
diff --git composer/composer_main.cc composer/composer_main.cc
index 51acd415b..d98cfbe0f 100644
--- composer/composer_main.cc
+++ composer/composer_main.cc
@@ -31,7 +31,6 @@
 #include <memory>
 #include <string>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "composer/composer.h"
 #include "composer/composition_interface.h"
@@ -39,8 +38,9 @@
 #include "protocol/commands.pb.h"
 #include "protocol/config.pb.h"
 #include "transliteration/transliteration.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, table, "system://romanji-hiragana.tsv",
+ABSL_FLAG(std::string, table, "system://romanji-hiragana.tsv",
           "preedit conversion table file.");
 
 using ::mozc::commands::Request;
@@ -50,7 +50,7 @@ int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
   mozc::composer::Table table;
-  table.LoadFromFile(mozc::GetFlag(FLAGS_table).c_str());
+  table.LoadFromFile(absl::GetFlag(FLAGS_table).c_str());
   std::unique_ptr<mozc::composer::Composer> composer(
       new mozc::composer::Composer(&table, &Request::default_instance(),
                                    &Config::default_instance()));
diff --git composer/composer_test.cc composer/composer_test.cc
index c589c542d..2d365a469 100644
--- composer/composer_test.cc
+++ composer/composer_test.cc
@@ -2514,7 +2514,7 @@ TEST_F(ComposerTest, InputModesChangeWhenCursorMoves) {
   }
 }
 
-TEST_F(ComposerTest, ShuoldCommit) {
+TEST_F(ComposerTest, ShouldCommit) {
   table_->AddRuleWithAttributes("ka", "[KA]", "", DIRECT_INPUT);
   table_->AddRuleWithAttributes("tt", "[X]", "t", DIRECT_INPUT);
   table_->AddRuleWithAttributes("ta", "[TA]", "", NO_TABLE_ATTRIBUTE);
diff --git composer/internal/BUILD composer/internal/BUILD
index 9ca7887c5..66f0b7130 100644
--- composer/internal/BUILD
+++ composer/internal/BUILD
@@ -184,10 +184,10 @@ cc_binary_mozc(
     srcs = ["composition_main.cc"],
     deps = [
         ":composition",
-        "//base:flags",
         "//base:init_mozc",
         "//composer:composition_interface",
         "//composer:table",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -243,9 +243,9 @@ cc_binary_mozc(
     srcs = ["converter_main.cc"],
     deps = [
         ":converter",
-        "//base:flags",
         "//base:init_mozc",
         "//composer:table",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -301,7 +301,6 @@ cc_library_mozc(
         ":composition_input",
         ":typing_model",
         "//base",
-        "//base:flags",
         "//base:port",
         "//base/protobuf",
         "//base/protobuf:repeated_field",
@@ -310,6 +309,7 @@ cc_library_mozc(
         "//composer:type_corrected_query",
         "//config:config_handler",
         "//protocol:config_proto",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
diff --git composer/internal/char_chunk_test.cc composer/internal/char_chunk_test.cc
index 9b8c9243c..12dac3eda 100644
--- composer/internal/char_chunk_test.cc
+++ composer/internal/char_chunk_test.cc
@@ -1026,7 +1026,7 @@ TEST(CharChunkTest, Combine) {
     EXPECT_EQ("LRRR", rhs.raw());
   }
 
-  {  // lhs' ambigous is empty.
+  {  // lhs' ambiguous is empty.
     CharChunk lhs(Transliterators::CONVERSION_STRING, nullptr);
     CharChunk rhs(Transliterators::CONVERSION_STRING, nullptr);
 
@@ -1047,7 +1047,7 @@ TEST(CharChunkTest, Combine) {
     EXPECT_EQ("LRRR", rhs.raw());
   }
 
-  {  // rhs' ambigous is empty.
+  {  // rhs' ambiguous is empty.
     CharChunk lhs(Transliterators::CONVERSION_STRING, nullptr);
     CharChunk rhs(Transliterators::CONVERSION_STRING, nullptr);
 
diff --git composer/internal/composition_main.cc composer/internal/composition_main.cc
index 82e63fe84..0fec00464 100644
--- composer/internal/composition_main.cc
+++ composer/internal/composition_main.cc
@@ -30,19 +30,19 @@
 #include <iostream>  // NOLINT
 #include <sstream>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "composer/internal/composition.h"
 #include "composer/table.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, table, "system://romanji-hiragana.tsv",
+ABSL_FLAG(std::string, table, "system://romanji-hiragana.tsv",
           "preedit conversion table file.");
 
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
   mozc::composer::Table table;
-  table.LoadFromFile(mozc::GetFlag(FLAGS_table).c_str());
+  table.LoadFromFile(absl::GetFlag(FLAGS_table).c_str());
 
   mozc::composer::Composition composition(&table);
 
diff --git composer/internal/converter_main.cc composer/internal/converter_main.cc
index 2c92d0d31..c091f50dd 100644
--- composer/internal/converter_main.cc
+++ composer/internal/converter_main.cc
@@ -30,19 +30,19 @@
 #include <iostream>  // NOLINT
 #include <string>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "composer/internal/converter.h"
 #include "composer/table.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, table, "system://romanji-hiragana.tsv",
+ABSL_FLAG(std::string, table, "system://romanji-hiragana.tsv",
           "preedit conversion table file.");
 
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
   mozc::composer::Table table;
-  table.LoadFromFile(mozc::GetFlag(FLAGS_table).c_str());
+  table.LoadFromFile(absl::GetFlag(FLAGS_table).c_str());
 
   mozc::composer::Converter converter(table);
 
diff --git composer/internal/transliterator_interface.h composer/internal/transliterator_interface.h
index d335b422e..e112761d4 100644
--- composer/internal/transliterator_interface.h
+++ composer/internal/transliterator_interface.h
@@ -52,7 +52,7 @@ class TransliteratorInterface {
   // Split raw and converted strings based on the transliteration
   // rule.  If raw or converted could not be deterministically split,
   // fall back strings are fill and false is returned.  The first
-  // arugment, position, is in character (rather than byte).
+  // argument, position, is in character (rather than byte).
   //
   // Expected usage examples:
   // - HiraganaTransliterator(1, "kk", "っk") => true
diff --git composer/internal/transliterators.cc composer/internal/transliterators.cc
index 1f7e52dbb..c57dc3cb0 100644
--- composer/internal/transliterators.cc
+++ composer/internal/transliterators.cc
@@ -90,7 +90,7 @@ class ConversionStringSelector : public TransliteratorInterface {
     return converted;
   }
 
-  // NOTE(komatsu): The first argument, size_t postion, should not be
+  // NOTE(komatsu): The first argument, size_t position, should not be
   // const because this function overrides the virtual function of
   // TransliterateInterface whose first argument is not const.
   // Otherwise the Windows compiler (cl.exe) raises an error.
diff --git composer/internal/transliterators.h composer/internal/transliterators.h
index 650056a4e..e74e3d6ea 100644
--- composer/internal/transliterators.h
+++ composer/internal/transliterators.h
@@ -55,7 +55,7 @@ class Transliterators {
     // Returns half ascii.
     HALF_ASCII,
     // Special transliterator.
-    // Use locally asigned transliterator.
+    // Use locally assigned transliterator.
     // Many methods don't accept this value.
     LOCAL,
 
diff --git composer/internal/typing_corrector.cc composer/internal/typing_corrector.cc
index da444d9ff..e15b3c041 100644
--- composer/internal/typing_corrector.cc
+++ composer/internal/typing_corrector.cc
@@ -35,7 +35,6 @@
 #include <string>
 #include <vector>
 
-#include "base/flags.h"
 #include "base/port.h"
 #include "composer/internal/composition.h"
 #include "composer/internal/composition_input.h"
@@ -44,6 +43,7 @@
 #include "composer/type_corrected_query.h"
 #include "config/config_handler.h"
 #include "protocol/config.pb.h"
+#include "absl/flags/flag.h"
 #include "absl/strings/string_view.h"
 
 namespace mozc {
diff --git composer/key_parser_test.cc composer/key_parser_test.cc
index 200a4bb67..68cfa0034 100644
--- composer/key_parser_test.cc
+++ composer/key_parser_test.cc
@@ -125,7 +125,7 @@ TEST(KeyParserTest, SpecialKeys) {
       std::make_pair("home", commands::KeyEvent::HOME),
       std::make_pair("end", commands::KeyEvent::END),
       std::make_pair("space", commands::KeyEvent::SPACE),
-      std::make_pair("ascii", commands::KeyEvent::TEXT_INPUT),  // depricated
+      std::make_pair("ascii", commands::KeyEvent::TEXT_INPUT),  // deprecated
       std::make_pair("textinput", commands::KeyEvent::TEXT_INPUT),
       std::make_pair("tab", commands::KeyEvent::TAB),
       std::make_pair("pageup", commands::KeyEvent::PAGE_UP),
diff --git config/BUILD config/BUILD
index 35e49e053..aaa40f119 100644
--- config/BUILD
+++ config/BUILD
@@ -67,7 +67,6 @@ cc_test_mozc(
         ":config_handler",
         "//base",
         "//base:file_util",
-        "//base:flags",
         "//base:logging",
         "//base:mozc_hash_set",
         "//base:port",
@@ -77,6 +76,7 @@ cc_test_mozc(
         "//protocol:config_proto",
         "//testing:gunit_main",
         "//testing:mozctest",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
@@ -108,12 +108,12 @@ cc_test_mozc(
         ":config_handler",
         ":stats_config_util",
         "//base:file_util",
-        "//base:flags",
         "//base:singleton",
         "//base:system_util",
         "//base:win_api_test_helper",
         "//protocol:config_proto",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -152,9 +152,9 @@ cc_test_mozc(
         ":character_form_manager",
         ":config_handler",
         "//base",
-        "//base:flags",
         "//base:system_util",
         "//protocol:config_proto",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
diff --git config/character_form_manager.h config/character_form_manager.h
index 65b3528af..36ae66092 100644
--- config/character_form_manager.h
+++ config/character_form_manager.h
@@ -130,7 +130,7 @@ class CharacterFormManager {
   //  form1=Half form2=Full
   //
   // If input1 and input2 have mixed form types and the result
-  // is ambigous, this function returns false.
+  // is ambiguous, this function returns false.
   //
   // Ambiguous case:
   //  input1="ABC１２３" input2="ＡＢＣ123"
diff --git config/character_form_manager_test.cc config/character_form_manager_test.cc
index 8e055f30d..d0ef380f2 100644
--- config/character_form_manager_test.cc
+++ config/character_form_manager_test.cc
@@ -31,12 +31,12 @@
 
 #include <string>
 
-#include "base/flags.h"
 #include "base/system_util.h"
 #include "config/config_handler.h"
 #include "protocol/config.pb.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace config {
@@ -45,7 +45,7 @@ class CharacterFormManagerTest : public ::testing::Test {
  public:
   void SetUp() override {
     // set default user profile directory
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     CharacterFormManager *manager =
         CharacterFormManager::GetCharacterFormManager();
     manager->SetDefaultRule();
diff --git config/config_handler.cc config/config_handler.cc
index de8d56ae8..71e01b20d 100644
--- config/config_handler.cc
+++ config/config_handler.cc
@@ -131,7 +131,7 @@ bool ConfigHandlerImpl::GetStoredConfig(Config *config) const {
   return true;
 }
 
-// set config and rewirte internal data
+// set config and rewrite internal data
 bool ConfigHandlerImpl::SetConfigInternal(const Config &config) {
   stored_config_.CopyFrom(config);
 
diff --git config/config_handler_test.cc config/config_handler_test.cc
index 01584d6c2..43dd9a5a8 100644
--- config/config_handler_test.cc
+++ config/config_handler_test.cc
@@ -37,7 +37,6 @@
 #include <string>
 
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/mozc_hash_set.h"
 #include "base/port.h"
@@ -48,6 +47,7 @@
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
 #include "testing/base/public/mozctest.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 namespace mozc {
@@ -57,7 +57,7 @@ namespace {
 class ConfigHandlerTest : public ::testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     default_config_filename_ = ConfigHandler::GetConfigFileName();
     Config default_config;
     ConfigHandler::GetDefaultConfig(&default_config);
@@ -97,7 +97,7 @@ TEST_F(ConfigHandlerTest, SetConfig) {
   Config output;
 
   const std::string config_file = FileUtil::JoinPath(
-      mozc::GetFlag(FLAGS_test_tmpdir), "mozc_config_test_tmp");
+      absl::GetFlag(FLAGS_test_tmpdir), "mozc_config_test_tmp");
   FileUtil::Unlink(config_file);
   ScopedSetConfigFileName scoped_config_file_name(config_file);
   EXPECT_EQ(config_file, ConfigHandler::GetConfigFileName());
@@ -157,7 +157,7 @@ TEST_F(ConfigHandlerTest, SetImposedConfig) {
   Config output;
 
   const std::string config_file = FileUtil::JoinPath(
-      mozc::GetFlag(FLAGS_test_tmpdir), "mozc_config_test_tmp");
+      absl::GetFlag(FLAGS_test_tmpdir), "mozc_config_test_tmp");
   FileUtil::Unlink(config_file);
   ScopedSetConfigFileName scoped_config_file_name(config_file);
   ASSERT_TRUE(ConfigHandler::Reload())
@@ -232,7 +232,7 @@ TEST_F(ConfigHandlerTest, ConfigFileNameConfig) {
       std::string("config") + std::to_string(config::CONFIG_VERSION);
 
   const std::string filename =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), config_file);
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), config_file);
   FileUtil::Unlink(filename);
   Config input;
   ConfigHandler::SetConfig(input);
diff --git config/stats_config_util_test.cc config/stats_config_util_test.cc
index 4efe077c7..1dd968409 100644
--- config/stats_config_util_test.cc
+++ config/stats_config_util_test.cc
@@ -33,12 +33,12 @@
 #include <string>
 
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/singleton.h"
 #include "base/system_util.h"
 #include "base/win_api_test_helper.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 #ifdef OS_ANDROID
 #include "config/config_handler.h"
@@ -672,7 +672,7 @@ TEST(StatsConfigUtilTestWin, IsEnabled) {
 #ifdef OS_ANDROID
 TEST(StatsConfigUtilTestAndroid, DefaultValueTest) {
   const string config_file = FileUtil::JoinPath(
-      mozc::GetFlag(FLAGS_test_tmpdir), "mozc_stats_config_util_test_tmp");
+      absl::GetFlag(FLAGS_test_tmpdir), "mozc_stats_config_util_test_tmp");
   FileUtil::Unlink(config_file);
   ConfigHandler::SetConfigFileName(config_file);
   EXPECT_EQ(config_file, ConfigHandler::GetConfigFileName());
diff --git converter/BUILD converter/BUILD
index 76c50e178..67c9e4ca2 100644
--- converter/BUILD
+++ converter/BUILD
@@ -596,9 +596,9 @@ cc_test_mozc(
         "//base",
         "//base:file_stream",
         "//base:file_util",
-        "//base:flags",
         "//testing:gunit_main",
         "//testing:mozctest",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
@@ -625,7 +625,6 @@ cc_binary_mozc(
         "//base",
         "//base:file_stream",
         "//base:file_util",
-        "//base:flags",
         "//base:init_mozc",
         "//base:logging",
         "//base:number_util",
@@ -641,6 +640,7 @@ cc_binary_mozc(
         "//protocol:config_proto",
         "//request:conversion_request",
         "//session:request_test_util",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -788,11 +788,11 @@ cc_binary_mozc(
     deps = [
         ":quality_regression_util",
         "//base",
-        "//base:flags",
         "//base:init_mozc",
         "//base:util",
         "//engine:engine_factory",
         "//engine:engine_interface",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
diff --git converter/candidate_filter.cc converter/candidate_filter.cc
index a0543a08c..0033766b2 100644
--- converter/candidate_filter.cc
+++ converter/candidate_filter.cc
@@ -65,7 +65,7 @@ const size_t kMaxCandidatesSize = 200;  // how many candidates we expand
 // cost(B) - cost(A) = -500 * [log(prob(B)) - log (C * prob(B)) ]
 //                   = -500 * [-log(C) + log(prob(B)) - log(prob(B))]
 //                   = 500 * log(C)
-// This implies that it is more reasonable to filter candiates
+// This implies that it is more reasonable to filter candidates
 // by an absolute difference of costs between cost(B) and cost(A).
 //
 // Here's "C" and cost-diff relation:
diff --git converter/candidate_filter_test.cc converter/candidate_filter_test.cc
index f99174d49..9fbb6aa40 100644
--- converter/candidate_filter_test.cc
+++ converter/candidate_filter_test.cc
@@ -173,7 +173,7 @@ TEST_F(CandidateFilterTest, FilterTest) {
     filter->Reset();
   }
 
-  // Check if a canidate is active before appending many candidates.
+  // Check if a candidate is active before appending many candidates.
   Segment::Candidate *c4 = NewCandidate();
   for (size_t i = 0; i < arraysize(kRequestTypes); ++i) {
     EXPECT_EQ(CandidateFilter::GOOD_CANDIDATE,
diff --git converter/converter_interface.h converter/converter_interface.h
index 12074f946..2553fc2b2 100644
--- converter/converter_interface.h
+++ converter/converter_interface.h
@@ -159,7 +159,7 @@ class ConverterInterface {
       Segments *segments, const std::vector<size_t> &candidate_index) const = 0;
 
   // Resize segment_index-th segment by offset_length.
-  // offset_lenth can be negative.
+  // offset_length can be negative.
   virtual bool ResizeSegment(Segments *segments,
                              const ConversionRequest &request,
                              size_t segment_index, int offset_length) const = 0;
diff --git converter/converter_main.cc converter/converter_main.cc
index 0f513914b..b9e745a01 100644
--- converter/converter_main.cc
+++ converter/converter_main.cc
@@ -36,7 +36,6 @@
 
 #include "base/file_stream.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/number_util.h"
@@ -56,24 +55,25 @@
 #include "protocol/config.pb.h"
 #include "request/conversion_request.h"
 #include "session/request_test_util.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(int32, max_conversion_candidates_size, 200,
+ABSL_FLAG(int32, max_conversion_candidates_size, 200,
           "maximum candidates size");
-MOZC_FLAG(string, user_profile_dir, "", "path to user profile directory");
-MOZC_FLAG(string, engine_name, "default",
+ABSL_FLAG(std::string, user_profile_dir, "", "path to user profile directory");
+ABSL_FLAG(std::string, engine_name, "default",
           "Shortcut to select engine_data_path from name: (default|oss|mock)");
-MOZC_FLAG(string, engine_type, "desktop", "Engine type: (desktop|mobile)");
-MOZC_FLAG(bool, output_debug_string, true,
+ABSL_FLAG(std::string, engine_type, "desktop", "Engine type: (desktop|mobile)");
+ABSL_FLAG(bool, output_debug_string, true,
           "output debug string for each input");
-MOZC_FLAG(bool, show_meta_candidates, false, "if true, show meta candidates");
+ABSL_FLAG(bool, show_meta_candidates, false, "if true, show meta candidates");
 
 // Advanced options for data files.  These are automatically set when --engine
 // is used but they can be overridden by specifying these flags.
-MOZC_FLAG(string, engine_data_path, "",
+ABSL_FLAG(std::string, engine_data_path, "",
           "Path to engine data file. This overrides the default data path "
           "for engine_name.");
-MOZC_FLAG(string, magic, "", "Expected magic number of data file");
-MOZC_FLAG(string, id_def, "",
+ABSL_FLAG(std::string, magic, "", "Expected magic number of data file");
+ABSL_FLAG(std::string, id_def, "",
           "id.def file for POS IDs. If provided, show human readable "
           "POS instead of ID number");
 
@@ -93,7 +93,7 @@ class PosIdPrintUtil {
 
  private:
   PosIdPrintUtil()
-      : pos_id_(new InputFileStream(mozc::GetFlag(FLAGS_id_def).c_str())),
+      : pos_id_(new InputFileStream(absl::GetFlag(FLAGS_id_def).c_str())),
         pos_id_printer_(new internal::PosIdPrinter(pos_id_.get())) {}
 
   std::string IdToStringInternal(int id) const {
@@ -238,7 +238,7 @@ void PrintSegment(size_t num, size_t segments_size, const Segment &segment,
         << SegmentTypeToString(segment.segment_type()) << "] ----------"
         << std::endl
         << segment.key() << std::endl;
-  if (mozc::GetFlag(FLAGS_show_meta_candidates)) {
+  if (absl::GetFlag(FLAGS_show_meta_candidates)) {
     for (int i = 0; i < segment.meta_candidates_size(); ++i) {
       PrintCandidate(segment, -i - 1, segment.meta_candidate(i), os);
     }
@@ -271,7 +271,7 @@ bool ExecCommand(const ConverterInterface &converter, Segments *segments,
   const Config config;
 
   segments->set_max_conversion_candidates_size(
-      mozc::GetFlag(FLAGS_max_conversion_candidates_size));
+      absl::GetFlag(FLAGS_max_conversion_candidates_size));
 
   if (func == "startconversion" || func == "start" || func == "s") {
     CHECK_FIELDS_LENGTH(2);
@@ -441,56 +441,56 @@ bool IsConsistentEngineNameAndType(const std::string &engine_name,
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
-  if (!mozc::GetFlag(FLAGS_user_profile_dir).empty()) {
+  if (!absl::GetFlag(FLAGS_user_profile_dir).empty()) {
     mozc::SystemUtil::SetUserProfileDirectory(
-        mozc::GetFlag(FLAGS_user_profile_dir));
+        absl::GetFlag(FLAGS_user_profile_dir));
   }
 
   std::string mozc_runfiles_dir = ".";
-  if (mozc::GetFlag(FLAGS_engine_data_path).empty()) {
+  if (absl::GetFlag(FLAGS_engine_data_path).empty()) {
     const auto path_and_magic = mozc::SelectDataFileFromName(
-        mozc_runfiles_dir, mozc::GetFlag(FLAGS_engine_name));
-    mozc::SetFlag(&FLAGS_engine_data_path, path_and_magic.first);
-    mozc::SetFlag(&FLAGS_magic, path_and_magic.second);
+        mozc_runfiles_dir, absl::GetFlag(FLAGS_engine_name));
+    absl::SetFlag(&FLAGS_engine_data_path, path_and_magic.first);
+    absl::SetFlag(&FLAGS_magic, path_and_magic.second);
   }
-  CHECK(!mozc::GetFlag(FLAGS_engine_data_path).empty())
+  CHECK(!absl::GetFlag(FLAGS_engine_data_path).empty())
       << "--engine_data_path or --engine is invalid: "
-      << "--engine_data_path=" << mozc::GetFlag(FLAGS_engine_data_path) << " "
-      << "--engine_name=" << mozc::GetFlag(FLAGS_engine_name);
+      << "--engine_data_path=" << absl::GetFlag(FLAGS_engine_data_path) << " "
+      << "--engine_name=" << absl::GetFlag(FLAGS_engine_name);
 
-  if (mozc::GetFlag(FLAGS_id_def).empty()) {
-    mozc::SetFlag(&FLAGS_id_def,
+  if (absl::GetFlag(FLAGS_id_def).empty()) {
+    absl::SetFlag(&FLAGS_id_def,
                   mozc::SelectIdDefFromName(mozc_runfiles_dir,
-                                            mozc::GetFlag(FLAGS_engine_name)));
+                                            absl::GetFlag(FLAGS_engine_name)));
   }
 
-  std::cout << "Engine type: " << mozc::GetFlag(FLAGS_engine_type)
-            << "\nData file: " << mozc::GetFlag(FLAGS_engine_data_path)
-            << "\nid.def: " << mozc::GetFlag(FLAGS_id_def) << std::endl;
+  std::cout << "Engine type: " << absl::GetFlag(FLAGS_engine_type)
+            << "\nData file: " << absl::GetFlag(FLAGS_engine_data_path)
+            << "\nid.def: " << absl::GetFlag(FLAGS_id_def) << std::endl;
 
   std::unique_ptr<mozc::DataManager> data_manager(new mozc::DataManager);
   const auto status = data_manager->InitFromFile(
-      mozc::GetFlag(FLAGS_engine_data_path), mozc::GetFlag(FLAGS_magic));
+      absl::GetFlag(FLAGS_engine_data_path), absl::GetFlag(FLAGS_magic));
   CHECK_EQ(status, mozc::DataManager::Status::OK);
 
   mozc::commands::Request request;
   std::unique_ptr<mozc::EngineInterface> engine;
-  if (mozc::GetFlag(FLAGS_engine_type) == "desktop") {
+  if (absl::GetFlag(FLAGS_engine_type) == "desktop") {
     engine = mozc::Engine::CreateDesktopEngine(std::move(data_manager)).value();
-  } else if (mozc::GetFlag(FLAGS_engine_type) == "mobile") {
+  } else if (absl::GetFlag(FLAGS_engine_type) == "mobile") {
     engine = mozc::Engine::CreateMobileEngine(std::move(data_manager)).value();
     mozc::commands::RequestForUnitTest::FillMobileRequest(&request);
   } else {
     LOG(FATAL) << "Invalid type: --engine_type="
-               << mozc::GetFlag(FLAGS_engine_type);
+               << absl::GetFlag(FLAGS_engine_type);
     return 0;
   }
 
   mozc::ConverterInterface *converter = engine->GetConverter();
   CHECK(converter);
 
-  if (!mozc::IsConsistentEngineNameAndType(mozc::GetFlag(FLAGS_engine_name),
-                                           mozc::GetFlag(FLAGS_engine_type))) {
+  if (!mozc::IsConsistentEngineNameAndType(absl::GetFlag(FLAGS_engine_name),
+                                           absl::GetFlag(FLAGS_engine_type))) {
     LOG(WARNING) << "Engine name and type do not match.";
   }
 
@@ -499,7 +499,7 @@ int main(int argc, char **argv) {
 
   while (!std::getline(std::cin, line).fail()) {
     if (mozc::ExecCommand(*converter, &segments, line, request)) {
-      if (mozc::GetFlag(FLAGS_output_debug_string)) {
+      if (absl::GetFlag(FLAGS_output_debug_string)) {
         mozc::PrintSegments(segments, &std::cout);
       }
     } else {
diff --git converter/converter_test.cc converter/converter_test.cc
index e4b63f55a..2617035e0 100644
--- converter/converter_test.cc
+++ converter/converter_test.cc
@@ -836,7 +836,7 @@ TEST_F(ConverterTest, Regression3437022) {
   const std::string kValue2 = "電話";
 
   {
-    // Make sure converte result is one segment
+    // Make sure convert result is one segment
     EXPECT_TRUE(converter->StartConversion(&segments, kKey1 + kKey2));
     EXPECT_EQ(1, segments.conversion_segments_size());
     EXPECT_EQ(kValue1 + kValue2,
diff --git converter/gen_segmenter_bitarray.cc converter/gen_segmenter_bitarray.cc
index 6de0d6c43..f055857c6 100644
--- converter/gen_segmenter_bitarray.cc
+++ converter/gen_segmenter_bitarray.cc
@@ -55,7 +55,7 @@ class StateTable {
     idarray_.resize(size);
   }
 
-  // |str| is an 1-dimentional row (or column) represented in byte array.
+  // |str| is an 1-dimensional row (or column) represented in byte array.
   void Add(uint16 id, absl::string_view str) {
     CHECK_LT(id, idarray_.size());
 #ifdef ABSL_USES_STD_STRING_VIEW
diff --git converter/immutable_converter.cc converter/immutable_converter.cc
index 72b17bc47..9cdd92fe3 100644
--- converter/immutable_converter.cc
+++ converter/immutable_converter.cc
@@ -332,14 +332,14 @@ void ImmutableConverterImpl::InsertDummyCandidates(Segment *segment,
           ? nullptr
           : segment->mutable_candidate(segment->candidates_size() - 1);
 
-  // Insert a dummy candiate whose content_value is katakana.
+  // Insert a dummy candidate whose content_value is katakana.
   // If functional_key() is empty, no need to make a dummy candidate.
   if (segment->candidates_size() > 0 &&
       segment->candidates_size() < expand_size &&
       !segment->candidate(0).functional_key().empty() &&
       Util::GetScriptType(segment->candidate(0).content_key) ==
           Util::HIRAGANA) {
-    // Use last_candidate as a refernce of cost.
+    // Use last_candidate as a reference of cost.
     // Use top_candidate as a refarence of lid/rid and key/value.
     DCHECK(top_candidate);
     DCHECK(last_candidate);
@@ -469,7 +469,7 @@ bool ImmutableConverterImpl::ResegmentArabicNumberAndSuffix(
         continue;
       }
 
-      // not compatibile
+      // not compatible
       if (number_value != number_key) {
         LOG(WARNING) << "Incompatible key/value number pair";
         continue;
@@ -545,7 +545,7 @@ bool ImmutableConverterImpl::ResegmentPrefixAndArabicNumber(
         continue;
       }
 
-      // not compatibile
+      // not compatible
       if (number_value != number_key) {
         LOG(WARNING) << "Incompatible key/value number pair";
         continue;
diff --git converter/immutable_converter_interface.h converter/immutable_converter_interface.h
index ac34db102..b116d092e 100644
--- converter/immutable_converter_interface.h
+++ converter/immutable_converter_interface.h
@@ -48,7 +48,7 @@ class ImmutableConverterInterface {
   virtual bool Convert(Segments *segments) const;
 
   // This method should be pure-virtual method in theory.
-  // However, to keep the backward compatibility untill the deprecation of
+  // However, to keep the backward compatibility until the deprecation of
   // Conversion method, we provide the default implementation.
   // Please see the .cc file.
   virtual bool ConvertForRequest(const ConversionRequest &request,
diff --git converter/key_corrector.cc converter/key_corrector.cc
index dc6574b2c..0eaa94a1f 100644
--- converter/key_corrector.cc
+++ converter/key_corrector.cc
@@ -452,7 +452,7 @@ bool KeyCorrector::CorrectKey(const std::string &key, InputMode mode,
         rev_alignment_.push_back(len + i);
       }
     } else {
-      // NOT a one to one maping, we take fist/last alignment only
+      // NOT a one to one mapping, we take fist/last alignment only
       alignment_.push_back(org_len);
       for (size_t i = 1; i < mblen; ++i) {
         alignment_.push_back(kInvalidPos);
diff --git converter/lattice.h converter/lattice.h
index 3d92b1f47..269d55237 100644
--- converter/lattice.h
+++ converter/lattice.h
@@ -48,7 +48,7 @@ class Lattice {
 
   NodeAllocator *node_allocator() const;
 
-  // set key and initalizes lattice with key.
+  // set key and initializes lattice with key.
   void SetKey(absl::string_view key);
 
   // return key.
diff --git converter/nbest_generator.cc converter/nbest_generator.cc
index 8d1f56bbd..6014eb3b4 100644
--- converter/nbest_generator.cc
+++ converter/nbest_generator.cc
@@ -289,7 +289,7 @@ bool NBestGenerator::Next(const std::string &original_key,
   //
   // Example:
   // |left_node| => |node1| => |node2| => |node3| => |right_node|.
-  // |node1| .. |node2| consists of a candidate.
+  // |node1| .. |node3| consists of a candidate.
   //
   // cost = (left_node->cost - begin_node_->cost) +
   //        trans(left_node, node1) + node1->wcost +
@@ -313,7 +313,7 @@ bool NBestGenerator::Next(const std::string &original_key,
   // Insert Viterbi best result here to make sure that
   // the top result is Viterbi best result.
   if (!viterbi_result_checked_) {
-    // Use CandiadteFilter so that filter is initialized with the
+    // Use CandidateFilter so that filter is initialized with the
     // Viterbi-best path.
     switch (InsertTopResult(original_key, candidate, request_type)) {
       case CandidateFilter::GOOD_CANDIDATE:
@@ -495,7 +495,7 @@ NBestGenerator::BoundaryCheckResult NBestGenerator::CheckOnlyMid(
     return VALID;
   }
 
-  // is_boundary is true if there is a grammer-based boundary
+  // is_boundary is true if there is a grammar-based boundary
   // between lnode and rnode
   const bool is_boundary = (lnode->node_type == Node::HIS_NODE ||
                             segmenter_->IsBoundary(*lnode, *rnode, false));
@@ -521,7 +521,7 @@ NBestGenerator::BoundaryCheckResult NBestGenerator::CheckOnlyEdge(
     return VALID;
   }
 
-  // is_boundary is true if there is a grammer-based boundary
+  // is_boundary is true if there is a grammar-based boundary
   // between lnode and rnode
   const bool is_boundary = (lnode->node_type == Node::HIS_NODE ||
                             segmenter_->IsBoundary(*lnode, *rnode, true));
@@ -542,7 +542,7 @@ NBestGenerator::BoundaryCheckResult NBestGenerator::CheckStrict(
     return VALID;
   }
 
-  // is_boundary is true if there is a grammer-based boundary
+  // is_boundary is true if there is a grammar-based boundary
   // between lnode and rnode
   const bool is_boundary = (lnode->node_type == Node::HIS_NODE ||
                             segmenter_->IsBoundary(*lnode, *rnode, false));
diff --git converter/nbest_generator.h converter/nbest_generator.h
index 1eedd3006..958c892f8 100644
--- converter/nbest_generator.h
+++ converter/nbest_generator.h
@@ -57,7 +57,7 @@ class NBestGenerator {
     //   Candidate edge:      |  candidate  |
     //   Nodes:        |Node A|Node B|Node C|Node D|
 
-    // For normal converison.
+    // For normal conversion.
     //  Candidate boundary is strictly same as inner boundary.
     // A-B: Should be the boundary
     // B-C: Should not be the boundary
@@ -79,7 +79,7 @@ class NBestGenerator {
     ONLY_EDGE,
   };
 
-  // Try to enumurate N-best results between begin_node and end_node.
+  // Try to enumerate N-best results between begin_node and end_node.
   NBestGenerator(
       const dictionary::SuppressionDictionary *suppression_dictionary,
       const Segmenter *segmenter, const Connector *connector,
diff --git converter/pos_id_printer_test.cc converter/pos_id_printer_test.cc
index 0d099d6e9..be8a2437f 100644
--- converter/pos_id_printer_test.cc
+++ converter/pos_id_printer_test.cc
@@ -34,9 +34,9 @@
 
 #include "base/file_stream.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "testing/base/public/gunit.h"
 #include "testing/base/public/mozctest.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 namespace mozc {
diff --git converter/quality_regression_main.cc converter/quality_regression_main.cc
index 94b6aa905..0b7cea0b4 100644
--- converter/quality_regression_main.cc
+++ converter/quality_regression_main.cc
@@ -32,14 +32,14 @@
 #include <string>
 #include <vector>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/util.h"
 #include "converter/quality_regression_util.h"
 #include "engine/engine_factory.h"
 #include "engine/engine_interface.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, test_file, "", "regression test file");
+ABSL_FLAG(std::string, test_file, "", "regression test file");
 
 using mozc::EngineFactory;
 using mozc::EngineInterface;
@@ -52,7 +52,7 @@ int main(int argc, char **argv) {
   QualityRegressionUtil util(engine->GetConverter());
 
   std::vector<QualityRegressionUtil::TestItem> items;
-  QualityRegressionUtil::ParseFile(mozc::GetFlag(FLAGS_test_file), &items);
+  QualityRegressionUtil::ParseFile(absl::GetFlag(FLAGS_test_file), &items);
 
   for (size_t i = 0; i < items.size(); ++i) {
     std::string actual_value;
diff --git converter/segmenter.cc converter/segmenter.cc
index 9d31f8fce..362461e1d 100644
--- converter/segmenter.cc
+++ converter/segmenter.cc
@@ -91,7 +91,7 @@ bool Segmenter::IsBoundary(const Node &lnode, const Node &rnode,
   // This hack is for handling ambiguous bunsetsu segmentation.
   // e.g. "かみ|にかく" => "紙|に書く" or "紙二角".
   // If we segment "に書く" into two segments, "二角" is never be shown.
-  // There exits some implicit assumpution that user expects that his/her input
+  // There exits some implicit assumpution that user expects that their input
   // becomes one bunsetu. So, it would be better to keep "二角" even after "紙".
   if (lnode.attributes & Node::STARTS_WITH_PARTICLE) {
     return false;
diff --git data/images/mac/BUILD data/images/mac/BUILD
index bd6eb9bcc..9fc04923a 100644
--- data/images/mac/BUILD
+++ data/images/mac/BUILD
@@ -30,5 +30,11 @@
 
 exports_files([
     "candidate_window_logo.tiff",
+    "direct.tiff",
+    "full_ascii.tiff",
+    "full_katakana.tiff",
+    "half_ascii.tiff",
+    "half_katakana.tiff",
+    "hiragana.tiff",
     "product_icon.icns",
 ])
diff --git data/installer/BUILD data/installer/BUILD
index dcd9e0736..78dc3c546 100644
--- data/installer/BUILD
+++ data/installer/BUILD
@@ -28,7 +28,7 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-exports_files(glob(["*"]))
+exports_files(["credits_en.html"])
 
 genrule(
     name = "android_asset_licenses",
diff --git data/installer/credits_en.html data/installer/credits_en.html
index df694e8ad..ab1796683 100644
--- data/installer/credits_en.html
+++ data/installer/credits_en.html
@@ -47,7 +47,7 @@
   white-space:pre-wrap;
 }
 .licence h3 {
-  margin-top:0px;
+  margin-top:0;
 }
 </style>
 </head>
diff --git data/test/calculator/gen_test.py data/test/calculator/gen_test.py
index 98f99d84b..fa11d6118 100644
--- data/test/calculator/gen_test.py
+++ data/test/calculator/gen_test.py
@@ -47,7 +47,7 @@
 # values of ans are really correct, the script itself does "test-for-test"
 # using python's eval() function. Namely, after building an expression tree,
 # we generate a python expression corresponding to the tree and compare its
-# value with that of the the direct evaluation. This test runs automatically
+# value with that of the direct evaluation. This test runs automatically
 # inside the script, but you can also write it to a file by specifying
 # --py_output option. Furthermore, passing --cc_output options enables you to
 # generate C++ code, respectively, that warns about expressions if results in
@@ -287,7 +287,7 @@ def eval(self):
 
   def build_test_expr(self):
     # If the child expression is one of the following, then we can omit
-    # parentheses becase of precedence.
+    # parentheses because of precedence.
     if (isinstance(self._expr, Number) or
         isinstance(self._expr, UnaryExpr) or
         isinstance(self._expr, Group)):
diff --git data/version/mozc_version_template.bzl data/version/mozc_version_template.bzl
index b60a9ccbb..4c848ce8f 100644
--- data/version/mozc_version_template.bzl
+++ data/version/mozc_version_template.bzl
@@ -33,7 +33,7 @@ MAJOR = 2
 MINOR = 26
 
 # Number to be increased. This value may be replaced by other tools.
-BUILD = 4276
+BUILD = 4282
 
 # Represent the platform and release channel.
 REVISION = 100
diff --git data_manager/BUILD data_manager/BUILD
index 98732e8ff..951241038 100644
--- data_manager/BUILD
+++ data_manager/BUILD
@@ -172,11 +172,11 @@ cc_test_mozc(
         ":dataset_writer",
         "//base:file_stream",
         "//base:file_util",
-        "//base:flags",
         "//base:obfuscator_support",
         "//base:util",
         "//testing:gunit_main",
         "//testing:mozctest",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
@@ -189,11 +189,11 @@ cc_binary_mozc(
         "//base",
         "//base:file_stream",
         "//base:file_util",
-        "//base:flags",
         "//base:init_mozc_buildtool",
         "//base:logging",
         "//base:number_util",
         "//base:util",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
diff --git data_manager/dataset_writer_main.cc data_manager/dataset_writer_main.cc
index dc279bdda..2ada473b1 100644
--- data_manager/dataset_writer_main.cc
+++ data_manager/dataset_writer_main.cc
@@ -47,23 +47,23 @@
 
 #include "base/file_stream.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/number_util.h"
 #include "base/util.h"
 #include "data_manager/dataset_writer.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, magic, "", "Hex-encoded magic number to be embedded");
-MOZC_FLAG(string, output, "", "Output file");
+ABSL_FLAG(std::string, magic, "", "Hex-encoded magic number to be embedded");
+ABSL_FLAG(std::string, output, "", "Output file");
 
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
   std::string magic;
-  CHECK(mozc::Util::Unescape(mozc::GetFlag(FLAGS_magic), &magic))
+  CHECK(mozc::Util::Unescape(absl::GetFlag(FLAGS_magic), &magic))
       << "magic number is not a proper hex-escaped string: "
-      << mozc::GetFlag(FLAGS_magic);
+      << absl::GetFlag(FLAGS_magic);
 
   struct Input {
     Input(const std::string &n, int a, const std::string &f)
@@ -87,12 +87,12 @@ int main(int argc, char **argv) {
                         params[2]);
   }
 
-  CHECK(!mozc::GetFlag(FLAGS_output).empty()) << "--output is required";
+  CHECK(!absl::GetFlag(FLAGS_output).empty()) << "--output is required";
 
   // DataSetWriter directly writes to the specified stream, so if it fails for
   // an input, the output contains a partial result.  To avoid such partial file
   // creation, write to a temporary file then rename it.
-  const std::string tmpfile = mozc::GetFlag(FLAGS_output) + ".tmp";
+  const std::string tmpfile = absl::GetFlag(FLAGS_output) + ".tmp";
   {
     mozc::DataSetWriter writer(magic);
     for (const auto &input : inputs) {
@@ -105,9 +105,9 @@ int main(int argc, char **argv) {
     writer.Finish(&output);
     output.close();
   }
-  CHECK(mozc::FileUtil::AtomicRename(tmpfile, mozc::GetFlag(FLAGS_output)))
+  CHECK(mozc::FileUtil::AtomicRename(tmpfile, absl::GetFlag(FLAGS_output)))
       << "Failed to rename " << tmpfile << " to "
-      << mozc::GetFlag(FLAGS_output);
+      << absl::GetFlag(FLAGS_output);
 
   return 0;
 }
diff --git data_manager/dataset_writer_test.cc data_manager/dataset_writer_test.cc
index 14a5664ed..c76b537c3 100644
--- data_manager/dataset_writer_test.cc
+++ data_manager/dataset_writer_test.cc
@@ -34,12 +34,12 @@
 
 #include "base/file_stream.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/unverified_sha1.h"
 #include "base/util.h"
 #include "data_manager/dataset.pb.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace {
@@ -54,7 +54,7 @@ void SetEntry(const string &name, uint64 offset, uint64 size,
 TEST(DatasetWriterTest, Write) {
   // Create a dummy file to be packed.
   const string &in =
-      FileUtil::JoinPath({mozc::GetFlag(FLAGS_test_tmpdir), "in"});
+      FileUtil::JoinPath({absl::GetFlag(FLAGS_test_tmpdir), "in"});
   {
     OutputFileStream f(in.c_str(), std::ios_base::out | std::ios_base::binary);
     f.write("m\0zc\xEF", 5);
diff --git data_manager/mozc_data.bzl data_manager/mozc_data.bzl
index 276158a66..3bd943718 100644
--- data_manager/mozc_data.bzl
+++ data_manager/mozc_data.bzl
@@ -404,10 +404,10 @@ def mozc_dataset(
         copts = ["-Wno-parentheses"],
         deps = [
             "//base",
-            "//base:flags",
             "//base:init_mozc_buildtool",
             "//converter:gen_segmenter_bitarray",
             "//:macro",
+            "@com_google_absl//absl/flags:flag",
         ],
     )
 
diff --git data_manager/oss/gen_oss_segmenter_bitarray_main.cc data_manager/oss/gen_oss_segmenter_bitarray_main.cc
index 6d5675933..7eb971b65 100644
--- data_manager/oss/gen_oss_segmenter_bitarray_main.cc
+++ data_manager/oss/gen_oss_segmenter_bitarray_main.cc
@@ -27,24 +27,25 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "converter/gen_segmenter_bitarray.h"
+#include "absl/flags/flag.h"
 
 namespace {
 #include "data_manager/oss/segmenter_inl.inc"
 }
 
-MOZC_FLAG(string, output_size_info, "", "Serialized SegmenterDataSizeInfo");
-MOZC_FLAG(string, output_ltable, "", "LTable array");
-MOZC_FLAG(string, output_rtable, "", "RTable array");
-MOZC_FLAG(string, output_bitarray, "", "Segmenter bitarray");
+ABSL_FLAG(std::string, output_size_info, "",
+          "Serialized SegmenterDataSizeInfo");
+ABSL_FLAG(std::string, output_ltable, "", "LTable array");
+ABSL_FLAG(std::string, output_rtable, "", "RTable array");
+ABSL_FLAG(std::string, output_bitarray, "", "Segmenter bitarray");
 
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
   mozc::SegmenterBitarrayGenerator::GenerateBitarray(
       kLSize, kRSize, &IsBoundaryInternal,
-      mozc::GetFlag(FLAGS_output_size_info), mozc::GetFlag(FLAGS_output_ltable),
-      mozc::GetFlag(FLAGS_output_rtable), mozc::GetFlag(FLAGS_output_bitarray));
+      absl::GetFlag(FLAGS_output_size_info), absl::GetFlag(FLAGS_output_ltable),
+      absl::GetFlag(FLAGS_output_rtable), absl::GetFlag(FLAGS_output_bitarray));
   return 0;
 }
diff --git data_manager/testing/gen_mock_segmenter_bitarray_main.cc data_manager/testing/gen_mock_segmenter_bitarray_main.cc
index 4b4739a2f..15a692a88 100644
--- data_manager/testing/gen_mock_segmenter_bitarray_main.cc
+++ data_manager/testing/gen_mock_segmenter_bitarray_main.cc
@@ -27,24 +27,25 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "converter/gen_segmenter_bitarray.h"
+#include "absl/flags/flag.h"
 
 namespace {
 #include "data_manager/testing/segmenter_inl.inc"
 }
 
-MOZC_FLAG(string, output_size_info, "", "Serialized SegmenterDataSizeInfo");
-MOZC_FLAG(string, output_ltable, "", "LTable array");
-MOZC_FLAG(string, output_rtable, "", "RTable array");
-MOZC_FLAG(string, output_bitarray, "", "Segmenter bitarray");
+ABSL_FLAG(std::string, output_size_info, "",
+          "Serialized SegmenterDataSizeInfo");
+ABSL_FLAG(std::string, output_ltable, "", "LTable array");
+ABSL_FLAG(std::string, output_rtable, "", "RTable array");
+ABSL_FLAG(std::string, output_bitarray, "", "Segmenter bitarray");
 
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
   mozc::SegmenterBitarrayGenerator::GenerateBitarray(
       kLSize, kRSize, &IsBoundaryInternal,
-      mozc::GetFlag(FLAGS_output_size_info), mozc::GetFlag(FLAGS_output_ltable),
-      mozc::GetFlag(FLAGS_output_rtable), mozc::GetFlag(FLAGS_output_bitarray));
+      absl::GetFlag(FLAGS_output_size_info), absl::GetFlag(FLAGS_output_ltable),
+      absl::GetFlag(FLAGS_output_rtable), absl::GetFlag(FLAGS_output_bitarray));
   return 0;
 }
diff --git dictionary/BUILD dictionary/BUILD
index 18655cb58..d14deb922 100644
--- dictionary/BUILD
+++ dictionary/BUILD
@@ -188,7 +188,6 @@ cc_test_mozc(
         ":user_pos",
         ":user_pos_interface",
         "//base:file_util",
-        "//base:flags",
         "//base:logging",
         "//base:port",
         "//base:singleton",
@@ -201,6 +200,7 @@ cc_test_mozc(
         "//testing:mozctest",
         "//usage_stats",
         "//usage_stats:usage_stats_testing_util",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
         "@com_google_absl//absl/strings",
     ],
@@ -299,11 +299,11 @@ cc_test_mozc(
         ":user_dictionary_storage",
         "//base",
         "//base:file_util",
-        "//base:flags",
         "//base:system_util",
         "//protocol:user_dictionary_storage_proto",
         "//testing:gunit_main",
         "//testing:testing_util",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
@@ -337,13 +337,13 @@ cc_test_mozc(
         ":user_dictionary_session_handler",
         "//base:file_stream",
         "//base:file_util",
-        "//base:flags",
         "//base:system_util",
         "//base/protobuf",
         "//base/protobuf:repeated_field",
         "//protocol:user_dictionary_storage_proto",
         "//testing:gunit_main",
         "//testing:testing_util",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
@@ -380,12 +380,12 @@ cc_test_mozc(
         "//base",
         "//base:file_stream",
         "//base:file_util",
-        "//base:flags",
         "//base:logging",
         "//base:mmap",
         "//base:system_util",
         "//base:util",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -481,7 +481,6 @@ cc_library_mozc(
         ":pos_matcher_lib",
         "//base",
         "//base:file_stream",
-        "//base:flags",
         "//base:iterator_adapter",
         "//base:logging",
         "//base:multifile",
@@ -490,6 +489,7 @@ cc_library_mozc(
         "//base:stl_util",
         "//base:util",
         "//testing:gunit_prod",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
@@ -507,10 +507,10 @@ cc_test_mozc(
         ":text_dictionary_loader",
         "//base:file_stream",
         "//base:file_util",
-        "//base:flags",
         "//base:util",
         "//data_manager/testing:mock_data_manager",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -646,12 +646,12 @@ cc_binary_mozc(
         ":text_dictionary_loader",
         "//base",
         "//base:file_stream",
-        "//base:flags",
         "//base:init_mozc_buildtool",
         "//base:logging",
         "//base:util",
         "//data_manager",
         "//dictionary/system:system_dictionary_builder",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
diff --git dictionary/file/BUILD dictionary/file/BUILD
index 408609501..69b8cdc9f 100644
--- dictionary/file/BUILD
+++ dictionary/file/BUILD
@@ -84,9 +84,9 @@ cc_test_mozc(
         ":dictionary_file_builder",
         "//base",
         "//base:file_util",
-        "//base:flags",
         "//base:logging",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -166,10 +166,10 @@ cc_test_mozc(
         "//base",
         "//base:file_stream",
         "//base:file_util",
-        "//base:flags",
         "//base:logging",
         "//base:util",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
diff --git dictionary/file/codec_test.cc dictionary/file/codec_test.cc
index 44c1721d5..258d816f9 100644
--- dictionary/file/codec_test.cc
+++ dictionary/file/codec_test.cc
@@ -33,7 +33,6 @@
 
 #include "base/file_stream.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/util.h"
 #include "dictionary/file/codec_factory.h"
@@ -41,6 +40,7 @@
 #include "dictionary/file/section.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 namespace mozc {
@@ -49,7 +49,7 @@ namespace {
 
 class CodecTest : public ::testing::Test {
  public:
-  CodecTest() : test_file_(mozc::GetFlag(FLAGS_test_tmpdir) + "testfile.txt") {}
+  CodecTest() : test_file_(absl::GetFlag(FLAGS_test_tmpdir) + "testfile.txt") {}
 
  protected:
   void SetUp() override {
diff --git dictionary/file/dictionary_file_test.cc dictionary/file/dictionary_file_test.cc
index 2ad145f51..4e8e76621 100644
--- dictionary/file/dictionary_file_test.cc
+++ dictionary/file/dictionary_file_test.cc
@@ -33,21 +33,21 @@
 #include <string>
 
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "dictionary/file/codec_factory.h"
 #include "dictionary/file/dictionary_file_builder.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace dictionary {
 namespace {
 
 TEST(DictionaryFileTest, Basic) {
-  const std::string dfn = mozc::GetFlag(FLAGS_test_tmpdir) + "/test-dictionary";
-  const std::string fn1 = mozc::GetFlag(FLAGS_test_tmpdir) + "/sec1";
-  const std::string fn2 = mozc::GetFlag(FLAGS_test_tmpdir) + "/sec2";
+  const std::string dfn = absl::GetFlag(FLAGS_test_tmpdir) + "/test-dictionary";
+  const std::string fn1 = absl::GetFlag(FLAGS_test_tmpdir) + "/sec1";
+  const std::string fn2 = absl::GetFlag(FLAGS_test_tmpdir) + "/sec2";
 
   FILE *fp1 = fopen(fn1.c_str(), "w");
   CHECK(fp1) << "failed to open temporary file";
diff --git dictionary/gen_system_dictionary_data_main.cc dictionary/gen_system_dictionary_data_main.cc
index 81400bf04..e10fc8e28 100644
--- dictionary/gen_system_dictionary_data_main.cc
+++ dictionary/gen_system_dictionary_data_main.cc
@@ -39,7 +39,6 @@
 #include <vector>
 
 #include "base/file_stream.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/util.h"
@@ -48,11 +47,12 @@
 #include "dictionary/pos_matcher.h"
 #include "dictionary/system/system_dictionary_builder.h"
 #include "dictionary/text_dictionary_loader.h"
+#include "absl/flags/flag.h"
 #include "absl/strings/string_view.h"
 
-MOZC_FLAG(string, input, "", "space separated input text files");
-MOZC_FLAG(string, user_pos_manager_data, "", "user pos manager data");
-MOZC_FLAG(string, output, "", "output binary file");
+ABSL_FLAG(std::string, input, "", "space separated input text files");
+ABSL_FLAG(std::string, user_pos_manager_data, "", "user pos manager data");
+ABSL_FLAG(std::string, output, "", "output binary file");
 
 namespace mozc {
 namespace {
@@ -95,7 +95,7 @@ int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
   std::string system_dictionary_input, reading_correction_input;
-  mozc::GetInputFileName(mozc::GetFlag(FLAGS_input), &system_dictionary_input,
+  mozc::GetInputFileName(absl::GetFlag(FLAGS_input), &system_dictionary_input,
                          &reading_correction_input);
 
   // User POS manager data for build tools has no magic number.
@@ -103,10 +103,10 @@ int main(int argc, char **argv) {
   mozc::DataManager data_manager;
   const mozc::DataManager::Status status =
       data_manager.InitUserPosManagerDataFromFile(
-          mozc::GetFlag(FLAGS_user_pos_manager_data), kMagicNumber);
+          absl::GetFlag(FLAGS_user_pos_manager_data), kMagicNumber);
   CHECK_EQ(status, mozc::DataManager::Status::OK)
       << "Failed to initialize data manager from "
-      << mozc::GetFlag(FLAGS_user_pos_manager_data);
+      << absl::GetFlag(FLAGS_user_pos_manager_data);
 
   const mozc::dictionary::POSMatcher pos_matcher(
       data_manager.GetPOSMatcherData());
@@ -118,8 +118,8 @@ int main(int argc, char **argv) {
   builder.BuildFromTokens(loader.tokens());
 
   std::unique_ptr<std::ostream> output_stream(new mozc::OutputFileStream(
-      mozc::GetFlag(FLAGS_output).c_str(), std::ios::out | std::ios::binary));
-  builder.WriteToStream(mozc::GetFlag(FLAGS_output), output_stream.get());
+      absl::GetFlag(FLAGS_output).c_str(), std::ios::out | std::ios::binary));
+  builder.WriteToStream(absl::GetFlag(FLAGS_output), output_stream.get());
 
   return 0;
 }
diff --git dictionary/suppression_dictionary.cc dictionary/suppression_dictionary.cc
index ed5e6219e..9720aaa03 100644
--- dictionary/suppression_dictionary.cc
+++ dictionary/suppression_dictionary.cc
@@ -98,7 +98,7 @@ bool SuppressionDictionary::IsEmpty() const {
 bool SuppressionDictionary::SuppressEntry(const std::string &key,
                                           const std::string &value) const {
   if (dic_.empty()) {
-    // Almost all users don't use word supresssion function.
+    // Almost all users don't use word suppression function.
     // We can return false as early as possible
     return false;
   }
diff --git dictionary/suppression_dictionary.h dictionary/suppression_dictionary.h
index 80669eeb6..dd71fa626 100644
--- dictionary/suppression_dictionary.h
+++ dictionary/suppression_dictionary.h
@@ -46,10 +46,10 @@ class SuppressionDictionary {
 
   // Locks dictionary.
   // Need to lock before calling AddEntry() or Clear().
-  // When the dictionary is locked, Supress() return false.
+  // When the dictionary is locked, Suppress() return false.
   //
   // NOTE:
-  // Lock() and SupressWord() must be called synchronously.
+  // Lock() and SuppressWord() must be called synchronously.
   void Lock();
 
   // Unlocks dictionary.
@@ -67,7 +67,7 @@ class SuppressionDictionary {
   // Returns true if SuppressionDictionary doesn't have any entries.
   bool IsEmpty() const;
 
-  // Returns true if |word| should be suppressed.  If the current dictionay is
+  // Returns true if |word| should be suppressed.  If the current dictionary is
   // "locked" via Lock() method, this function always return false.  Lock() and
   // SuppressWord() must be called synchronously.
   bool SuppressEntry(const std::string &key, const std::string &value) const;
diff --git dictionary/suppression_dictionary_test.cc dictionary/suppression_dictionary_test.cc
index 086d3924a..5e275af51 100644
--- dictionary/suppression_dictionary_test.cc
+++ dictionary/suppression_dictionary_test.cc
@@ -42,7 +42,7 @@ namespace mozc {
 namespace dictionary {
 namespace {
 
-TEST(SupressionDictionary, BasicTest) {
+TEST(SuppressionDictionary, BasicTest) {
   SuppressionDictionary *dic = Singleton<SuppressionDictionary>::get();
   CHECK(dic);
 
@@ -126,7 +126,7 @@ class DictionaryLoaderThread : public Thread {
   }
 };
 
-TEST(SupressionDictionary, ThreadTest) {
+TEST(SuppressionDictionary, ThreadTest) {
   SuppressionDictionary *dic = Singleton<SuppressionDictionary>::get();
   CHECK(dic);
 
diff --git dictionary/system/BUILD dictionary/system/BUILD
index abe03f02e..e7e52dc34 100644
--- dictionary/system/BUILD
+++ dictionary/system/BUILD
@@ -164,7 +164,6 @@ cc_library_mozc(
         ":codec",
         ":words_info",
         "//base:file_stream",
-        "//base:flags",
         "//base:logging",
         "//base:mozc_hash_set",
         "//base:port",
@@ -200,7 +199,6 @@ cc_test_mozc(
         ":system_dictionary",
         ":system_dictionary_builder",
         "//base:file_util",
-        "//base:flags",
         "//base:logging",
         "//base:port",
         "//base:stl_util",
@@ -253,13 +251,13 @@ cc_test_mozc(
         ":system_dictionary",
         "//base",
         "//base:file_stream",
-        "//base:flags",
         "//base:logging",
         "//base:util",
         "//dictionary:dictionary_test_util",
         "//request:conversion_request",
         "//testing:gunit_main",
         "//testing/base/public:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
diff --git dictionary/system/system_dictionary.cc dictionary/system/system_dictionary.cc
index 2cffb3ab1..d0d19a0bd 100644
--- dictionary/system/system_dictionary.cc
+++ dictionary/system/system_dictionary.cc
@@ -862,7 +862,7 @@ class ReverseLookupCallbackWrapper : public DictionaryInterface::Callback {
 
 }  // namespace
 
-// Recursive implemention of depth-first prefix search with key expansion.
+// Recursive implementation of depth-first prefix search with key expansion.
 // Input parameters:
 //   key:
 //     The head address of the original key before applying codec.
diff --git dictionary/system/system_dictionary_builder.cc dictionary/system/system_dictionary_builder.cc
index f4645851e..6ddc84082 100644
--- dictionary/system/system_dictionary_builder.cc
+++ dictionary/system/system_dictionary_builder.cc
@@ -35,7 +35,6 @@
 #include <sstream>
 
 #include "base/file_stream.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/mozc_hash_set.h"
 #include "base/util.h"
@@ -51,9 +50,9 @@
 #include "storage/louds/louds_trie_builder.h"
 #include "absl/flags/flag.h"
 
-MOZC_FLAG(bool, preserve_intermediate_dictionary, false,
+ABSL_FLAG(bool, preserve_intermediate_dictionary, false,
           "preserve inetemediate dictionary file.");
-MOZC_FLAG(int32, min_key_length_to_use_small_cost_encoding, 6,
+ABSL_FLAG(int32, min_key_length_to_use_small_cost_encoding, 6,
           "minimum key length to use 1 byte cost encoding.");
 
 namespace mozc {
@@ -163,7 +162,7 @@ void SystemDictionaryBuilder::WriteToStream(
       file_codec_->GetSectionName(codec_->GetSectionNameForPos()));
   sections.push_back(frequent_pos_section);
 
-  if (mozc::GetFlag(FLAGS_preserve_intermediate_dictionary) &&
+  if (absl::GetFlag(FLAGS_preserve_intermediate_dictionary) &&
       !intermediate_output_file_base_path.empty()) {
     // Write out intermediate results to files.
     const std::string &basepath = intermediate_output_file_base_path;
@@ -366,7 +365,7 @@ void SystemDictionaryBuilder::SetCostType(KeyInfoList *key_info_list) const {
       TokenInfo *token_info = &key_info->tokens[i];
       const int key_len = Util::CharsLen(token_info->token->key);
       if (key_len >=
-          mozc::GetFlag(FLAGS_min_key_length_to_use_small_cost_encoding)) {
+          absl::GetFlag(FLAGS_min_key_length_to_use_small_cost_encoding)) {
         token_info->cost_type = TokenInfo::CAN_USE_SMALL_ENCODING;
       }
     }
diff --git dictionary/system/system_dictionary_test.cc dictionary/system/system_dictionary_test.cc
index c0ceee35f..9409fc597 100644
--- dictionary/system/system_dictionary_test.cc
+++ dictionary/system/system_dictionary_test.cc
@@ -38,7 +38,6 @@
 #include <vector>
 
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/port.h"
 #include "base/stl_util.h"
@@ -58,13 +57,15 @@
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
 #include "testing/base/public/mozctest.h"
+#include "absl/flags/declare.h"
+#include "absl/flags/flag.h"
 #include "absl/strings/string_view.h"
 
-MOZC_FLAG(int32, dictionary_test_size, 100000,
+ABSL_FLAG(int32, dictionary_test_size, 100000,
           "Dictionary size for this test.");
-MOZC_FLAG(int32, dictionary_reverse_lookup_test_size, 1000,
+ABSL_FLAG(int32, dictionary_reverse_lookup_test_size, 1000,
           "Number of tokens to run reverse lookup test.");
-MOZC_DECLARE_FLAG(int32, min_key_length_to_use_small_cost_encoding);
+ABSL_DECLARE_FLAG(int32, min_key_length_to_use_small_cost_encoding);
 
 namespace mozc {
 namespace dictionary {
@@ -75,11 +76,11 @@ class SystemDictionaryTest : public ::testing::Test {
       : pos_matcher_(mock_data_manager_.GetPOSMatcherData()),
         text_dict_(new TextDictionaryLoader(pos_matcher_)),
         dic_fn_(
-            FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "mozc.dic")) {
+            FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "mozc.dic")) {
     const std::string dic_path = mozc::testing::GetSourceFileOrDie(
         {"data", "dictionary_oss", "dictionary00.txt"});
     text_dict_->LoadWithLineLimit(dic_path, "",
-                                  mozc::GetFlag(FLAGS_dictionary_test_size));
+                                  absl::GetFlag(FLAGS_dictionary_test_size));
 
     convreq_.set_request(&request_);
     convreq_.set_config(&config_);
@@ -88,8 +89,8 @@ class SystemDictionaryTest : public ::testing::Test {
   void SetUp() override {
     // Don't use small cost encoding by default.
     original_flags_min_key_length_to_use_small_cost_encoding_ =
-        mozc::GetFlag(FLAGS_min_key_length_to_use_small_cost_encoding);
-    mozc::SetFlag(&FLAGS_min_key_length_to_use_small_cost_encoding,
+        absl::GetFlag(FLAGS_min_key_length_to_use_small_cost_encoding);
+    absl::SetFlag(&FLAGS_min_key_length_to_use_small_cost_encoding,
                   std::numeric_limits<int32>::max());
 
     request_.Clear();
@@ -97,7 +98,7 @@ class SystemDictionaryTest : public ::testing::Test {
   }
 
   void TearDown() override {
-    mozc::SetFlag(&FLAGS_min_key_length_to_use_small_cost_encoding,
+    absl::SetFlag(&FLAGS_min_key_length_to_use_small_cost_encoding,
                   original_flags_min_key_length_to_use_small_cost_encoding_);
 
     // This config initialization will be removed once ConversionRequest can
@@ -265,7 +266,7 @@ TEST_F(SystemDictionaryTest, NormalWord) {
   t0->rid = 70;
   source_tokens.push_back(t0.get());
   BuildSystemDictionary(source_tokens,
-                        mozc::GetFlag(FLAGS_dictionary_test_size));
+                        absl::GetFlag(FLAGS_dictionary_test_size));
 
   std::unique_ptr<SystemDictionary> system_dic =
       SystemDictionary::Builder(dic_fn_).Build().value();
@@ -322,7 +323,7 @@ TEST_F(SystemDictionaryTest, SameWord) {
     source_tokens.push_back(&tokens[i]);
   }
   BuildSystemDictionary(source_tokens,
-                        mozc::GetFlag(FLAGS_dictionary_test_size));
+                        absl::GetFlag(FLAGS_dictionary_test_size));
 
   std::unique_ptr<SystemDictionary> system_dic =
       SystemDictionary::Builder(dic_fn_).Build().value();
@@ -337,7 +338,7 @@ TEST_F(SystemDictionaryTest, SameWord) {
 TEST_F(SystemDictionaryTest, LookupAllWords) {
   const std::vector<Token *> &source_tokens = text_dict_->tokens();
   BuildSystemDictionary(source_tokens,
-                        mozc::GetFlag(FLAGS_dictionary_test_size));
+                        absl::GetFlag(FLAGS_dictionary_test_size));
 
   std::unique_ptr<SystemDictionary> system_dic =
       SystemDictionary::Builder(dic_fn_).Build().value();
@@ -708,7 +709,7 @@ TEST_F(SystemDictionaryTest, LookupReverse) {
   ASSERT_TRUE(system_dic) << "Failed to open dictionary source:" << dic_fn_;
   const size_t test_size =
       std::min(static_cast<size_t>(
-                   mozc::GetFlag(FLAGS_dictionary_reverse_lookup_test_size)),
+                   absl::GetFlag(FLAGS_dictionary_reverse_lookup_test_size)),
                source_tokens.size());
   for (size_t source_index = 0; source_index < test_size; ++source_index) {
     const Token &source_token = *source_tokens[source_index];
@@ -767,7 +768,7 @@ TEST_F(SystemDictionaryTest, LookupReverse) {
 TEST_F(SystemDictionaryTest, LookupReverseIndex) {
   const std::vector<Token *> &source_tokens = text_dict_->tokens();
   BuildSystemDictionary(source_tokens,
-                        mozc::GetFlag(FLAGS_dictionary_test_size));
+                        absl::GetFlag(FLAGS_dictionary_test_size));
 
   std::unique_ptr<SystemDictionary> system_dic_without_index =
       SystemDictionary::Builder(dic_fn_)
@@ -785,7 +786,7 @@ TEST_F(SystemDictionaryTest, LookupReverseIndex) {
       << "Failed to open dictionary source:" << dic_fn_;
 
   std::vector<Token *>::const_iterator it;
-  int size = mozc::GetFlag(FLAGS_dictionary_reverse_lookup_test_size);
+  int size = absl::GetFlag(FLAGS_dictionary_reverse_lookup_test_size);
   for (it = source_tokens.begin(); size > 0 && it != source_tokens.end();
        ++it, --size) {
     const Token &t = **it;
diff --git dictionary/text_dictionary_loader.cc dictionary/text_dictionary_loader.cc
index 5aea84a6a..d2b3618ab 100644
--- dictionary/text_dictionary_loader.cc
+++ dictionary/text_dictionary_loader.cc
@@ -40,7 +40,6 @@
 #include <vector>
 
 #include "base/file_stream.h"
-#include "base/flags.h"
 #include "base/iterator_adapter.h"
 #include "base/logging.h"
 #include "base/multifile.h"
@@ -49,9 +48,10 @@
 #include "base/util.h"
 #include "dictionary/dictionary_token.h"
 #include "dictionary/pos_matcher.h"
+#include "absl/flags/flag.h"
 #include "absl/strings/string_view.h"
 
-MOZC_FLAG(int32, tokens_reserve_size, 1400000,
+ABSL_FLAG(int32, tokens_reserve_size, 1400000,
           "Reserve the specified size of token buffer in advance.");
 
 namespace mozc {
@@ -168,7 +168,7 @@ void TextDictionaryLoader::LoadWithLineLimit(
 
   // Roughly allocate buffers for Token pointers.
   if (limit < 0) {
-    tokens_.reserve(mozc::GetFlag(FLAGS_tokens_reserve_size));
+    tokens_.reserve(absl::GetFlag(FLAGS_tokens_reserve_size));
     limit = std::numeric_limits<int>::max();
   } else {
     tokens_.reserve(limit);
diff --git dictionary/text_dictionary_loader_test.cc dictionary/text_dictionary_loader_test.cc
index 7bf174c6c..2f061f8db 100644
--- dictionary/text_dictionary_loader_test.cc
+++ dictionary/text_dictionary_loader_test.cc
@@ -35,13 +35,13 @@
 
 #include "base/file_stream.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/util.h"
 #include "data_manager/testing/mock_data_manager.h"
 #include "dictionary/dictionary_token.h"
 #include "dictionary/pos_matcher.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 using std::unique_ptr;
 
@@ -89,7 +89,7 @@ TEST_F(TextDictionaryLoaderTest, BasicTest) {
   }
 
   const std::string filename =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "test.tsv");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "test.tsv");
   {
     OutputFileStream ofs(filename.c_str());
     ofs << kTextLines;
@@ -214,9 +214,9 @@ TEST_F(TextDictionaryLoaderTest, RewriteSpecialTokenTest) {
 
 TEST_F(TextDictionaryLoaderTest, LoadMultipleFilesTest) {
   const std::string filename1 =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "test1.tsv");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "test1.tsv");
   const std::string filename2 =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "test2.tsv");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "test2.tsv");
   const std::string filename = filename1 + "," + filename2;
 
   {
@@ -242,9 +242,9 @@ TEST_F(TextDictionaryLoaderTest, ReadingCorrectionTest) {
   unique_ptr<TextDictionaryLoader> loader(CreateTextDictionaryLoader());
 
   const std::string dic_filename =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "test.tsv");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "test.tsv");
   const std::string reading_correction_filename = FileUtil::JoinPath(
-      mozc::GetFlag(FLAGS_test_tmpdir), "reading_correction.tsv");
+      absl::GetFlag(FLAGS_test_tmpdir), "reading_correction.tsv");
 
   {
     OutputFileStream ofs(dic_filename.c_str());
diff --git dictionary/user_dictionary_session.h dictionary/user_dictionary_session.h
index 82d3a251a..2137cdd80 100644
--- dictionary/user_dictionary_session.h
+++ dictionary/user_dictionary_session.h
@@ -71,7 +71,7 @@ class UserDictionarySession {
   // or not), creates an empty dictionary in the storage with the default name.
   UserDictionaryCommandStatus::Status LoadWithEnsuringNonEmptyStorage();
 
-  // Saves the data to local stroage.
+  // Saves the data to local storage.
   UserDictionaryCommandStatus::Status Save();
 
   // Undoes the last operation.
diff --git dictionary/user_dictionary_session_handler_test.cc dictionary/user_dictionary_session_handler_test.cc
index b45638cc5..c2208ec13 100644
--- dictionary/user_dictionary_session_handler_test.cc
+++ dictionary/user_dictionary_session_handler_test.cc
@@ -35,7 +35,6 @@
 
 #include "base/file_stream.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/protobuf/protobuf.h"
 #include "base/protobuf/repeated_field.h"
 #include "base/system_util.h"
@@ -43,6 +42,7 @@
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
 #include "testing/base/public/testing_util.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 namespace mozc {
@@ -68,7 +68,7 @@ class UserDictionarySessionHandlerTest : public ::testing::Test {
  protected:
   void SetUp() override {
     original_user_profile_directory_ = SystemUtil::GetUserProfileDirectory();
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     FileUtil::Unlink(GetUserDictionaryFile());
 
     handler_ = absl::make_unique<UserDictionarySessionHandler>();
@@ -89,7 +89,7 @@ class UserDictionarySessionHandlerTest : public ::testing::Test {
   }
 
   static std::string GetUserDictionaryFile() {
-    return FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "test.db");
+    return FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "test.db");
   }
 
   uint64 CreateSession() {
diff --git dictionary/user_dictionary_session_test.cc dictionary/user_dictionary_session_test.cc
index 229117cfc..3b9729aa4 100644
--- dictionary/user_dictionary_session_test.cc
+++ dictionary/user_dictionary_session_test.cc
@@ -34,13 +34,13 @@
 #endif  // OS_WIN
 
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/system_util.h"
 #include "dictionary/user_dictionary_storage.h"
 #include "protocol/user_dictionary_storage.pb.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
 #include "testing/base/public/testing_util.h"
+#include "absl/flags/flag.h"
 
 namespace {
 
@@ -61,7 +61,7 @@ class UserDictionarySessionTest : public ::testing::Test {
  protected:
   void SetUp() override {
     original_user_profile_directory_ = SystemUtil::GetUserProfileDirectory();
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     FileUtil::Unlink(GetUserDictionaryFile());
   }
 
@@ -72,9 +72,9 @@ class UserDictionarySessionTest : public ::testing::Test {
 
   static std::string GetUserDictionaryFile() {
 #ifndef OS_WIN
-    chmod(mozc::GetFlag(FLAGS_test_tmpdir).c_str(), 0777);
+    chmod(absl::GetFlag(FLAGS_test_tmpdir).c_str(), 0777);
 #endif  // OS_WIN
-    return FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "test.db");
+    return FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "test.db");
   }
 
   void ResetEntry(const std::string &key, const std::string &value,
@@ -217,7 +217,7 @@ TEST_F(UserDictionarySessionTest, DeleteDictionary) {
   EXPECT_EQ(kDummyId, session.storage().dictionaries(0).id());
 }
 
-TEST_F(UserDictionarySessionTest, DeleteDictionaryWithEnsuringNonEmptyStroage) {
+TEST_F(UserDictionarySessionTest, DeleteDictionaryWithEnsuringNonEmptyStorage) {
   UserDictionarySession session(GetUserDictionaryFile());
   session.SetDefaultDictionaryName("abcde");
 
diff --git dictionary/user_dictionary_storage.h dictionary/user_dictionary_storage.h
index 6d9e7ebb2..dd5b0cd43 100644
--- dictionary/user_dictionary_storage.h
+++ dictionary/user_dictionary_storage.h
@@ -113,7 +113,7 @@ class UserDictionaryStorage {
   //       is kept as is.
   bool Load();
 
-  // Serialzie user dictionary to local file.
+  // Serialize user dictionary to local file.
   // Need to call Lock() the dictionary before calling Save().
   bool Save();
 
@@ -166,7 +166,7 @@ class UserDictionaryStorage {
   static int CountSyncableDictionaries(
       const user_dictionary::UserDictionaryStorage &storage);
 
-  // maxium number of dictionaries this storage can hold
+  // maximum number of dictionaries this storage can hold
   static size_t max_dictionary_size();
 
   // maximum number of entries one dictionary can hold
diff --git dictionary/user_dictionary_storage_test.cc dictionary/user_dictionary_storage_test.cc
index 8af3b888c..d153f0fac 100644
--- dictionary/user_dictionary_storage_test.cc
+++ dictionary/user_dictionary_storage_test.cc
@@ -34,7 +34,6 @@
 
 #include "base/file_stream.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/mmap.h"
 #include "base/system_util.h"
@@ -43,6 +42,7 @@
 #include "dictionary/user_dictionary_util.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace {
@@ -66,7 +66,7 @@ class UserDictionaryStorageTest : public ::testing::Test {
  protected:
   void SetUp() override {
     backup_user_profile_directory_ = SystemUtil::GetUserProfileDirectory();
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     FileUtil::Unlink(GetUserDictionaryFile());
   }
 
@@ -76,7 +76,7 @@ class UserDictionaryStorageTest : public ::testing::Test {
   }
 
   static std::string GetUserDictionaryFile() {
-    return FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "test.db");
+    return FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "test.db");
   }
 
  private:
@@ -217,7 +217,7 @@ TEST_F(UserDictionaryStorageTest, ExportTest) {
   }
 
   const std::string export_file =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "export.txt");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "export.txt");
 
   EXPECT_FALSE(storage.ExportDictionary(id + 1, export_file));
   EXPECT_TRUE(storage.ExportDictionary(id, export_file));
@@ -432,7 +432,7 @@ TEST_F(UserDictionaryStorageTest, ConvertSyncDictionariesToNormalDictionaries) {
 TEST_F(UserDictionaryStorageTest, Export) {
   const int kDummyDictionaryId = 10;
   const std::string kPath =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "exported_file");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "exported_file");
 
   {
     UserDictionaryStorage storage(GetUserDictionaryFile());
diff --git dictionary/user_dictionary_test.cc dictionary/user_dictionary_test.cc
index 1b1ea8b70..da3af7d32 100644
--- dictionary/user_dictionary_test.cc
+++ dictionary/user_dictionary_test.cc
@@ -38,7 +38,6 @@
 #include <vector>
 
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/port.h"
 #include "base/singleton.h"
@@ -59,6 +58,7 @@
 #include "testing/base/public/mozctest.h"
 #include "usage_stats/usage_stats.h"
 #include "usage_stats/usage_stats_testing_util.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 #include "absl/strings/string_view.h"
 
@@ -508,7 +508,7 @@ TEST_F(UserDictionaryTest, TestLookupExactWithSuggestionOnlyWords) {
 
   // Create dictionary
   const std::string filename = FileUtil::JoinPath(
-      mozc::GetFlag(FLAGS_test_tmpdir), "suggestion_only_test.db");
+      absl::GetFlag(FLAGS_test_tmpdir), "suggestion_only_test.db");
   FileUtil::Unlink(filename);
   UserDictionaryStorage storage(filename);
   {
@@ -571,7 +571,7 @@ TEST_F(UserDictionaryTest, IncognitoModeTest) {
 
 TEST_F(UserDictionaryTest, AsyncLoadTest) {
   const std::string filename = FileUtil::JoinPath(
-      mozc::GetFlag(FLAGS_test_tmpdir), "async_load_test.db");
+      absl::GetFlag(FLAGS_test_tmpdir), "async_load_test.db");
   FileUtil::Unlink(filename);
 
   // Create dictionary
@@ -624,7 +624,7 @@ TEST_F(UserDictionaryTest, TestSuppressionDictionary) {
   user_dic->WaitForReloader();
 
   const std::string filename = FileUtil::JoinPath(
-      mozc::GetFlag(FLAGS_test_tmpdir), "suppression_test.db");
+      absl::GetFlag(FLAGS_test_tmpdir), "suppression_test.db");
   FileUtil::Unlink(filename);
 
   UserDictionaryStorage storage(filename);
@@ -699,7 +699,7 @@ TEST_F(UserDictionaryTest, TestSuggestionOnlyWord) {
   user_dic->WaitForReloader();
 
   const std::string filename = FileUtil::JoinPath(
-      mozc::GetFlag(FLAGS_test_tmpdir), "suggestion_only_test.db");
+      absl::GetFlag(FLAGS_test_tmpdir), "suggestion_only_test.db");
   FileUtil::Unlink(filename);
 
   UserDictionaryStorage storage(filename);
diff --git engine/BUILD engine/BUILD
index 8527861ab..1ca71a3ea 100644
--- engine/BUILD
+++ engine/BUILD
@@ -79,11 +79,11 @@ cc_test_mozc(
     deps = [
         ":engine_builder",
         "//base:file_util",
-        "//base:flags",
         "//prediction:predictor_interface",
         "//protocol:engine_builder_proto",
         "//testing:gunit_main",
         "//testing:mozctest",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
diff --git engine/engine_builder_interface.h engine/engine_builder_interface.h
index 4c635e1b9..8e059e3bd 100644
--- engine/engine_builder_interface.h
+++ engine/engine_builder_interface.h
@@ -48,7 +48,7 @@ class EngineBuilderInterface {
 
   // Accepts data load request and sets |response->status()| to one of the
   // following values:
-  //   * ACCEPTED: Request is successfuly accepted.
+  //   * ACCEPTED: Request is successfully accepted.
   //   * ALREADY_RUNNING: The previous request is still being processed.
   virtual void PrepareAsync(const EngineReloadRequest &request,
                             EngineReloadResponse *response) = 0;
diff --git engine/engine_builder_test.cc engine/engine_builder_test.cc
index 6a5f65194..a5ff00e1c 100644
--- engine/engine_builder_test.cc
+++ engine/engine_builder_test.cc
@@ -32,11 +32,11 @@
 #include <string>
 
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "prediction/predictor_interface.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
 #include "testing/base/public/mozctest.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace {
@@ -83,11 +83,11 @@ TEST_F(EngineBuilderTest, PrepareAsync) {
     // Test request with install.  Since the requested file is moved,
     // |mock_data_path_| is copied to a temporary file.
     const std::string src_path =
-        FileUtil::JoinPath({mozc::GetFlag(FLAGS_test_tmpdir), "src.data"});
+        FileUtil::JoinPath({absl::GetFlag(FLAGS_test_tmpdir), "src.data"});
     ASSERT_TRUE(FileUtil::CopyFile(mock_data_path_, src_path));
 
     const std::string install_path =
-        FileUtil::JoinPath({mozc::GetFlag(FLAGS_test_tmpdir), "dst.data"});
+        FileUtil::JoinPath({absl::GetFlag(FLAGS_test_tmpdir), "dst.data"});
     request_.set_engine_type(EngineReloadRequest::MOBILE);
     request_.set_file_path(src_path);
     request_.set_install_location(install_path);
@@ -152,9 +152,9 @@ TEST_F(EngineBuilderTest, AsyncBuildWithInstall) {
       {EngineReloadRequest::MOBILE, "MobilePredictor"},
   };
   const std::string &tmp_src =
-      FileUtil::JoinPath({mozc::GetFlag(FLAGS_test_tmpdir), "src.data"});
+      FileUtil::JoinPath({absl::GetFlag(FLAGS_test_tmpdir), "src.data"});
   const std::string install_path =
-      FileUtil::JoinPath({mozc::GetFlag(FLAGS_test_tmpdir), "dst.data"});
+      FileUtil::JoinPath({absl::GetFlag(FLAGS_test_tmpdir), "dst.data"});
 
   for (const auto &test_case : kTestCases) {
     Clear();
diff --git gui/BUILD gui/BUILD
index e04879829..7dd39dfb8 100644
--- gui/BUILD
+++ gui/BUILD
@@ -28,23 +28,14 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-load("//:config.bzl", "BRANDING")
+load("//:build_defs.bzl", "info_plist_mozc")
 
 package(
     default_visibility = ["//gui:__subpackages__"],
 )
 
-genrule(
-    name = "gen_mozc_tool_info_plist",
-    srcs = [
-        "//base:mozc_version_txt",
-        "//data/mac:mozc_tool_info",
-    ],
+info_plist_mozc(
+    name = "mozc_tool_info_plist",
+    srcs = ["//data/mac:mozc_tool_info"],
     outs = ["mozc_tool_info.plist"],
-    cmd = ("$(location //build_tools:tweak_info_plist)" +
-           " --output $@" +
-           " --input $(location //data/mac:mozc_tool_info)" +
-           " --version_file $(location //base:mozc_version_txt)" +
-           " --branding " + BRANDING),
-    exec_tools = ["//build_tools:tweak_info_plist"],
 )
diff --git gui/config_dialog/config_dialog.h gui/config_dialog/config_dialog.h
index 14e1e6bf3..3627b9ca8 100644
--- gui/config_dialog/config_dialog.h
+++ gui/config_dialog/config_dialog.h
@@ -60,7 +60,7 @@ class ConfigDialog : public QDialog, private Ui::ConfigDialog {
   ConfigDialog();
   ~ConfigDialog() override;
 
-  // Methods defined in the 'slots' section (Qt's extention) will be processed
+  // Methods defined in the 'slots' section (Qt's extension) will be processed
   // by Qt's moc tool (moc.exe on Windows). Unfortunately, preprocessor macros
   // defined for C/C++ are not automatically passed into the moc tool.
   // For example, you need to call the moc tool with '-D' option as
diff --git gui/config_dialog/generic_table_editor.h gui/config_dialog/generic_table_editor.h
index d59695b66..d44ec03e3 100644
--- gui/config_dialog/generic_table_editor.h
+++ gui/config_dialog/generic_table_editor.h
@@ -70,7 +70,7 @@ class GenericTableEditorDialog : public QDialog,
   QTableWidget *mutable_table_widget();
   QMenu *mutable_edit_menu();
 
-  // impliments a method which returns default fileame
+  // implements a method which returns default fileame
   virtual std::string GetDefaultFilename() const = 0;
 
   // implements a method which loads
diff --git gui/config_dialog/keybinding_editor.h gui/config_dialog/keybinding_editor.h
index f08006ebc..b5f0d69ff 100644
--- gui/config_dialog/keybinding_editor.h
+++ gui/config_dialog/keybinding_editor.h
@@ -58,7 +58,7 @@ class KeyBindingEditor : public QDialog, private Ui::KeyBindingEditor {
   void SetBinding(const QString &binding);
 
   // For some reason, KeyBindingEditor lanuched by
-  // QItemDelegate looses focus. We overwrite
+  // QItemDelegate loses focus. We overwrite
   // setVisible() function to call raise() and activateWindow().
   void setVisible(bool visible) override {
     QWidget::setVisible(visible);
diff --git gui/config_dialog/keymap_editor.cc gui/config_dialog/keymap_editor.cc
index 8d329c633..48e62463e 100644
--- gui/config_dialog/keymap_editor.cc
+++ gui/config_dialog/keymap_editor.cc
@@ -104,7 +104,7 @@ class KeyMapValidator {
 #if defined(__APPLE__)
     // On Mac, we cannot customize keybindings for IME ON/OFF
     // So we do not show them.
-    // TODO(toshiyuki): remove them after implimenting IME ON/OFF for Mac
+    // TODO(toshiyuki): remove them after implementing IME ON/OFF for Mac
     invisible_commands_.insert(kIMEOnCommand);
     invisible_commands_.insert(kIMEOffCommand);
 #endif  // __APPLE__
diff --git gui/dictionary_tool/BUILD gui/dictionary_tool/BUILD
index f0987c52b..5030263b8 100644
--- gui/dictionary_tool/BUILD
+++ gui/dictionary_tool/BUILD
@@ -180,9 +180,9 @@ cc_qt_library_mozc(
     srcs = ["dictionary_tool_main.cc"],
     deps = [
         ":dictionary_tool",
-        "//base:flags",
         "//base:init_mozc",
         "//gui/base:gui_base",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
diff --git gui/dictionary_tool/dictionary_tool.h gui/dictionary_tool/dictionary_tool.h
index cc26021ed..0024cae94 100644
--- gui/dictionary_tool/dictionary_tool.h
+++ gui/dictionary_tool/dictionary_tool.h
@@ -126,7 +126,7 @@ class DictionaryTool : public QMainWindow, private Ui::DictionaryTool {
 
   // Show a dialog and get text for dictionary name from the user. The
   // first parameter is default text printed in a form. The second is
-  // message printed on the dialog. It returns an empty stirng
+  // message printed on the dialog. It returns an empty string
   // whenever a proper value for dictionary name is input.
   QString PromptForDictionaryName(const QString &text, const QString &label);
 
@@ -137,7 +137,7 @@ class DictionaryTool : public QMainWindow, private Ui::DictionaryTool {
   // These two functions are to start/stop monitoring data on the
   // table widget being changed. We validate the value on the widget
   // when the user edit it but the data can be modified
-  // programatically and validation is not necessary.
+  // programmatically and validation is not necessary.
   void StartMonitoringUserEdit();
   void StopMonitoringUserEdit();
 
@@ -155,7 +155,7 @@ class DictionaryTool : public QMainWindow, private Ui::DictionaryTool {
   // send Reload command to the server.
   void SaveAndReloadServer();
 
-  // 1. Shows a dialog box and get new |commnet|.
+  // 1. Shows a dialog box and get new |comment|.
   // 2. Changes the comemnt of all selected.
   void EditComment();
 
@@ -192,12 +192,12 @@ class DictionaryTool : public QMainWindow, private Ui::DictionaryTool {
   // not been saved.
   bool modified_;
 
-  // Holds information on whether dictionary entires are sorted, key
+  // Holds information on whether dictionary entries are sorted, key
   // column of sort and order of sort.
   //
   // Current implementation of sort may not be perfect. It doesn't
   // check if entries are already sorted when they are loaded nor
-  // whether modification is made keeping sorted entires sorted.
+  // whether modification is made keeping sorted entries sorted.
   struct SortState {
     bool sorted;
     int column;
diff --git gui/dictionary_tool/dictionary_tool_main.cc gui/dictionary_tool/dictionary_tool_main.cc
index c6701cb7f..cdf445431 100644
--- gui/dictionary_tool/dictionary_tool_main.cc
+++ gui/dictionary_tool/dictionary_tool_main.cc
@@ -27,8 +27,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
+#include "absl/flags/flag.h"
 
 #ifdef OS_WIN
 #include "base/winmain.h"
diff --git gui/error_message_dialog/BUILD gui/error_message_dialog/BUILD
index abc150ff4..9f85bcdd0 100644
--- gui/error_message_dialog/BUILD
+++ gui/error_message_dialog/BUILD
@@ -73,7 +73,6 @@ cc_qt_library_mozc(
     ],
     deps = [
         "//base:file_util",
-        "//base:flags",
         "//base:logging",
         "//base:port",
         "//base:process",
@@ -84,6 +83,7 @@ cc_qt_library_mozc(
         "//base:version",
         "//gui/base:gui_base",
         "//gui/base:singleton_window_helper",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
diff --git gui/error_message_dialog/error_message_dialog.cc gui/error_message_dialog/error_message_dialog.cc
index 87b344e60..9acf8fc8a 100644
--- gui/error_message_dialog/error_message_dialog.cc
+++ gui/error_message_dialog/error_message_dialog.cc
@@ -34,10 +34,10 @@
 #include <QtWidgets/QAbstractButton>
 #include <QtWidgets/QMessageBox>
 
-#include "base/flags.h"
 #include "gui/base/util.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, error_type, "", "type of error");
+ABSL_FLAG(std::string, error_type, "", "type of error");
 
 namespace mozc {
 namespace gui {
@@ -82,36 +82,36 @@ void DeleyedMessageDialogHandler::EnableOkButton() {
 void ErrorMessageDialog::Show() {
   // defining all literal messages inside Show() method
   // for easy i18n/i10n
-  if (mozc::GetFlag(FLAGS_error_type) == "server_timeout") {
+  if (absl::GetFlag(FLAGS_error_type) == "server_timeout") {
     OnFatal(
         QObject::tr("Conversion engine is not responding. "
                     "Please restart this application."));
-  } else if (mozc::GetFlag(FLAGS_error_type) == "server_broken_message") {
+  } else if (absl::GetFlag(FLAGS_error_type) == "server_broken_message") {
     OnFatal(QObject::tr(
         "Connecting to an incompatible conversion engine. "
         "Please restart your computer to enable [ProductName]. "
         "If this problem persists, please uninstall [ProductName] "
         "and install it again."));
-  } else if (mozc::GetFlag(FLAGS_error_type) == "server_version_mismatch") {
+  } else if (absl::GetFlag(FLAGS_error_type) == "server_version_mismatch") {
     OnFatal(QObject::tr(
         "Conversion engine has been upgraded. "
         "Please restart this application to enable conversion engine. "
         "If the problem persists, please restart your computer."));
-  } else if (mozc::GetFlag(FLAGS_error_type) == "server_shutdown") {
+  } else if (absl::GetFlag(FLAGS_error_type) == "server_shutdown") {
     OnFatal(
         QObject::tr("Conversion engine is killed unexceptionally. "
                     "Restarting the engine..."));
-  } else if (mozc::GetFlag(FLAGS_error_type) == "server_fatal") {
+  } else if (absl::GetFlag(FLAGS_error_type) == "server_fatal") {
     OnFatal(
         QObject::tr("Cannot start conversion engine. "
                     "Please restart your computer."));
-  } else if (mozc::GetFlag(FLAGS_error_type) == "renderer_version_mismatch") {
+  } else if (absl::GetFlag(FLAGS_error_type) == "renderer_version_mismatch") {
     OnFatal(
         QObject::tr("Candidate window renderer has been upgraded. "
                     "Please restart this application to enable new candidate "
                     "window renderer. "
                     "If the problem persists, please restart your computer."));
-  } else if (mozc::GetFlag(FLAGS_error_type) == "renderer_fatal") {
+  } else if (absl::GetFlag(FLAGS_error_type) == "renderer_fatal") {
     OnFatal(
         QObject::tr("Cannot start candidate window renderer. "
                     "Please restart your computer."));
diff --git gui/tool/BUILD gui/tool/BUILD
index a3beece3f..c6a358f72 100644
--- gui/tool/BUILD
+++ gui/tool/BUILD
@@ -40,11 +40,11 @@ cc_library_mozc(
     name = "prelauncher_lib",
     srcs = ["prelauncher_libmain.cc"],
     deps = [
-        "//base:flags",
         "//base:mac_util",
         "//client",
         "//client:client_interface",
         "//renderer:renderer_client",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -59,7 +59,7 @@ cc_qt_library_mozc(
     deps = [
         "//base:crash_report_handler",
         "//base:file_util",
-        "//base:flags",
+        "@com_google_absl//absl/flags:flag",
         "//base:init_mozc",
         "//base:logging",
         "//base:port",
diff --git gui/tool/mozc_tool.rc gui/tool/mozc_tool.rc
index b98f3a66a..ab446ce43 100644
Binary files gui/tool/mozc_tool.rc and gui/tool/mozc_tool.rc differ
diff --git gui/tool/mozc_tool_libmain.cc gui/tool/mozc_tool_libmain.cc
index 38cdda7c3..584465cf0 100644
--- gui/tool/mozc_tool_libmain.cc
+++ gui/tool/mozc_tool_libmain.cc
@@ -44,13 +44,14 @@
 
 #include "base/crash_report_handler.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/run_level.h"
 #include "base/util.h"
 #include "config/stats_config_util.h"
 #include "gui/base/debug_util.h"
+#include "absl/flags/declare.h"
+#include "absl/flags/flag.h"
 
 #ifdef __APPLE__
 #include "base/const.h"
@@ -60,8 +61,8 @@
 #include "gui/base/win_util.h"
 #endif  // OS_WIN
 
-MOZC_FLAG(string, mode, "about_dialog", "mozc_tool mode");
-MOZC_DECLARE_FLAG(string, error_type);
+ABSL_FLAG(std::string, mode, "about_dialog", "mozc_tool mode");
+ABSL_DECLARE_FLAG(string, error_type);
 
 // Run* are defiend in each qt module
 int RunAboutDialog(int argc, char *argv[]);
@@ -87,12 +88,12 @@ namespace {
 void SetFlagsFromEnv() {
   const char *mode = std::getenv("FLAGS_mode");
   if (mode != nullptr) {
-    mozc::SetFlag(&FLAGS_mode, mode);
+    absl::SetFlag(&FLAGS_mode, mode);
   }
 
   const char *error_type = std::getenv("FLAGS_error_type");
   if (error_type != nullptr) {
-    mozc::SetFlag(&FLAGS_error_type, error_type);
+    absl::SetFlag(&FLAGS_error_type, error_type);
   }
 }
 
@@ -115,24 +116,24 @@ int RunMozcTool(int argc, char *argv[]) {
   // name.
   string binary_name = mozc::FileUtil::Basename(argv[0]);
   if (binary_name == "AboutDialog") {
-    mozc::SetFlag(&FLAGS_mode, "about_dialog");
+    absl::SetFlag(&FLAGS_mode, "about_dialog");
   } else if (binary_name == "ConfigDialog") {
-    mozc::SetFlag(&FLAGS_mode, "config_dialog");
+    absl::SetFlag(&FLAGS_mode, "config_dialog");
   } else if (binary_name == "DictionaryTool") {
-    mozc::SetFlag(&FLAGS_mode, "dictionary_tool");
+    absl::SetFlag(&FLAGS_mode, "dictionary_tool");
   } else if (binary_name == "ErrorMessageDialog") {
-    mozc::SetFlag(&FLAGS_mode, "error_message_dialog");
+    absl::SetFlag(&FLAGS_mode, "error_message_dialog");
   } else if (binary_name == "WordRegisterDialog") {
-    mozc::SetFlag(&FLAGS_mode, "word_register_dialog");
+    absl::SetFlag(&FLAGS_mode, "word_register_dialog");
   } else if (binary_name == kProductPrefix "Prelauncher") {
     // The binary name of prelauncher is user visible in
     // "System Preferences" -> "Accounts" -> "Login items".
     // So we set kProductPrefix to the binary name.
-    mozc::SetFlag(&FLAGS_mode, "prelauncher");
+    absl::SetFlag(&FLAGS_mode, "prelauncher");
   }
 #endif
 
-  if (mozc::GetFlag(FLAGS_mode) != "administration_dialog" &&
+  if (absl::GetFlag(FLAGS_mode) != "administration_dialog" &&
       !mozc::RunLevel::IsValidClientRunLevel()) {
     return -1;
   }
@@ -145,34 +146,34 @@ int RunMozcTool(int argc, char *argv[]) {
   mozc::gui::WinUtil::KeepJumpListUpToDate();
 #endif  // OS_WIN
 
-  if (mozc::GetFlag(FLAGS_mode) == "config_dialog") {
+  if (absl::GetFlag(FLAGS_mode) == "config_dialog") {
     return RunConfigDialog(argc, argv);
-  } else if (mozc::GetFlag(FLAGS_mode) == "dictionary_tool") {
+  } else if (absl::GetFlag(FLAGS_mode) == "dictionary_tool") {
     return RunDictionaryTool(argc, argv);
-  } else if (mozc::GetFlag(FLAGS_mode) == "word_register_dialog") {
+  } else if (absl::GetFlag(FLAGS_mode) == "word_register_dialog") {
     return RunWordRegisterDialog(argc, argv);
-  } else if (mozc::GetFlag(FLAGS_mode) == "error_message_dialog") {
+  } else if (absl::GetFlag(FLAGS_mode) == "error_message_dialog") {
     return RunErrorMessageDialog(argc, argv);
-  } else if (mozc::GetFlag(FLAGS_mode) == "about_dialog") {
+  } else if (absl::GetFlag(FLAGS_mode) == "about_dialog") {
     return RunAboutDialog(argc, argv);
 #ifdef OS_WIN
-  } else if (mozc::GetFlag(FLAGS_mode) == "set_default_dialog") {
+  } else if (absl::GetFlag(FLAGS_mode) == "set_default_dialog") {
     // set_default_dialog is used on Windows only.
     return RunSetDefaultDialog(argc, argv);
-  } else if (mozc::GetFlag(FLAGS_mode) == "post_install_dialog") {
+  } else if (absl::GetFlag(FLAGS_mode) == "post_install_dialog") {
     // post_install_dialog is used on Windows only.
     return RunPostInstallDialog(argc, argv);
-  } else if (mozc::GetFlag(FLAGS_mode) == "administration_dialog") {
+  } else if (absl::GetFlag(FLAGS_mode) == "administration_dialog") {
     // administration_dialog is used on Windows only.
     return RunAdministrationDialog(argc, argv);
 #endif  // OS_WIN
 #ifdef __APPLE__
-  } else if (mozc::GetFlag(FLAGS_mode) == "prelauncher") {
+  } else if (absl::GetFlag(FLAGS_mode) == "prelauncher") {
     // Prelauncher is used on Mac only.
     return RunPrelaunchProcesses(argc, argv);
 #endif  // __APPLE__
   } else {
-    LOG(ERROR) << "Unknown mode: " << mozc::GetFlag(FLAGS_mode);
+    LOG(ERROR) << "Unknown mode: " << absl::GetFlag(FLAGS_mode);
     return -1;
   }
 
diff --git gui/tool/prelauncher_libmain.cc gui/tool/prelauncher_libmain.cc
index d149eaf8f..39d677c4b 100644
--- gui/tool/prelauncher_libmain.cc
+++ gui/tool/prelauncher_libmain.cc
@@ -31,7 +31,7 @@
 
 #include <memory>
 
-#include "base/flags.h"
+#include "absl/flags/flag.h"
 #ifdef __APPLE__
 #include "base/mac_util.h"
 #endif  // __APPLE__
@@ -39,13 +39,13 @@
 #include "renderer/renderer_client.h"
 
 #ifdef __APPLE__
-MOZC_FLAG(bool, register_prelauncher, false,
+ABSL_FLAG(bool, register_prelauncher, false,
           "Register prelauncher to login item.");
 #endif  // __APPLE__
 
 int RunPrelaunchProcesses(int argc, char *argv[]) {
 #ifdef __APPLE__
-  if (mozc::GetFlag(FLAGS_register_prelauncher)) {
+  if (absl::GetFlag(FLAGS_register_prelauncher)) {
     mozc::MacUtil::AddPrelauncherLoginItem();
   }
 #endif  // __APPLE__
diff --git ios/BUILD ios/BUILD
index 719fa5e64..7461df3fa 100644
--- ios/BUILD
+++ ios/BUILD
@@ -42,7 +42,6 @@ cc_library_mozc(
     ],
     deps = [
         "//base",
-        "//base:flags",
         "//base:logging",
         "//base:mutex",
         "//base:port",
@@ -58,6 +57,7 @@ cc_library_mozc(
         "//session:session_handler",
         "//session:session_handler_interface",
         "@com_google_absl//absl/base:core_headers",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -67,11 +67,11 @@ cc_binary_mozc(
     data = ["//data_manager/google:mozc.data"],
     deps = [
         ":ios_engine",
-        "//base:flags",
         "//base:init_mozc_buildtool",
         "//base:logging",
         "//base:util",
         "//protocol:candidates_proto",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
diff --git ios/ios_engine.cc ios/ios_engine.cc
index ea915128f..d5314342d 100644
--- ios/ios_engine.cc
+++ ios/ios_engine.cc
@@ -33,7 +33,6 @@
 #include <string>
 #include <utility>
 
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/mutex.h"
 #include "config/config_handler.h"
@@ -46,6 +45,7 @@
 #include "session/session.h"
 #include "session/session_handler.h"
 #include "session/session_handler_interface.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace ios {
@@ -169,7 +169,7 @@ IosEngine::InputConfigTuple IosEngine::GetInputConfigTupleFromLayoutName(
 void IosEngine::InitMozc() {
   // Output logs to stderr so that they are displayed in XCode's console.
   // This must be set before Logging::InitLogStream().
-  mozc::SetFlag(&FLAGS_logtostderr, true);
+  absl::SetFlag(&FLAGS_logtostderr, true);
   Logging::InitLogStream("MOZC_IOS_ENGINE");
 }
 
diff --git ios/ios_engine.h ios/ios_engine.h
index 934ffe398..dd93f1fa7 100644
--- ios/ios_engine.h
+++ ios/ios_engine.h
@@ -108,8 +108,8 @@ class IosEngine {
   //   * Another thread is using the underlying engine.
   // The second case is expected because this method is intended to be called by
   // a timer thread only when there's no key event for a while after a key press
-  // event is occured.  The use of underlying engine means some events have
-  // occured when the timer thread calls this method, so it's expected not to
+  // event is occurred.  The use of underlying engine means some events have
+  // occurred when the timer thread calls this method, so it's expected not to
   // send the special key to the engine.
   bool MaybeCreateNewChunk(commands::Command *command);
 
diff --git ios/ios_engine_main.cc ios/ios_engine_main.cc
index 21d6e5e71..d7724c6d5 100644
--- ios/ios_engine_main.cc
+++ ios/ios_engine_main.cc
@@ -31,17 +31,17 @@
 #include <iostream>
 #include <string>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/util.h"
 #include "ios/ios_engine.h"
 #include "protocol/candidates.pb.h"
+#include "absl/flags/flag.h"
 
 // mozc/data_manager/testing:mozc_dataset_for_testing is one of datafile.
-MOZC_FLAG(string, datafile, "", "Path to a data file to be used");
-MOZC_FLAG(int32, candsize, 3, "Maximum number of candidates");
-MOZC_FLAG(bool, show_full, false, "Display the debug string of output command");
+ABSL_FLAG(std::string, datafile, "", "Path to a data file to be used");
+ABSL_FLAG(int32, candsize, 3, "Maximum number of candidates");
+ABSL_FLAG(bool, show_full, false, "Display the debug string of output command");
 
 namespace {
 
@@ -69,7 +69,7 @@ void Convert(const std::string &query, mozc::ios::IosEngine *engine,
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
-  mozc::ios::IosEngine ios_engine(mozc::GetFlag(FLAGS_datafile));
+  mozc::ios::IosEngine ios_engine(absl::GetFlag(FLAGS_datafile));
 
   mozc::commands::Command command;
   mozc::config::Config config;
@@ -97,13 +97,13 @@ int main(int argc, char **argv) {
 
     Convert(query, &ios_engine, &command);
 
-    if (mozc::GetFlag(FLAGS_show_full)) {
+    if (absl::GetFlag(FLAGS_show_full)) {
       std::cout << command.Utf8DebugString() << std::endl;
     } else {
       std::cout << "----- preedit -----\n"
                 << command.output().preedit().Utf8DebugString() << std::endl;
       const auto &cands = command.output().candidates();
-      const int size = std::min(mozc::GetFlag(FLAGS_candsize),
+      const int size = std::min(absl::GetFlag(FLAGS_candsize),
                                 cands.candidate_size());
       for (int i = 0; i < size; ++i) {
         std::cout << "----- candidate " << i << " -----\n"
diff --git ipc/BUILD ipc/BUILD
index f947ecf33..94fd5a445 100644
--- ipc/BUILD
+++ ipc/BUILD
@@ -130,7 +130,6 @@ cc_test_mozc(
         "//base",
         "//base:file_stream",
         "//base:file_util",
-        "//base:flags",
         "//base:port",
         "//base:process_mutex",
         "//base:system_util",
@@ -138,6 +137,7 @@ cc_test_mozc(
         "//base:util",
         "//base:version",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -174,12 +174,12 @@ cc_test_mozc(
         ":ipc",
         ":ipc_test_util",
         "//base",
-        "//base:flags",
         "//base:port",
         "//base:system_util",
         "//base:thread",
         "//base:util",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -221,12 +221,12 @@ cc_test_mozc(
         ":named_event",
         "//base",
         "//base:clock",
-        "//base:flags",
         "//base:port",
         "//base:system_util",
         "//base:thread",
         "//base:util",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
@@ -268,12 +268,12 @@ cc_library_mozc(
 #     deps = [
 #         ":process_watch_dog",
 #         "//base",
-#         "//base:flags",
 #         "//base:init_mozc",
 #         "//base:logging",
 #         "//base:number_util",
 #         "//base:port",
 #         "//base:util",
+#         "@com_google_absl//absl/flags:flag",
 #     ],
 # )
 
diff --git ipc/ipc.h ipc/ipc.h
index 296656791..fe4c67128 100644
--- ipc/ipc.h
+++ ipc/ipc.h
@@ -184,7 +184,7 @@ class IPCClientFactoryInterface {
   virtual IPCClientInterface *NewClient(const std::string &name,
                                         const std::string &path_name) = 0;
 
-  // old interface for backward compatiblity.
+  // old interface for backward compatibility.
   // same as NewClient(name, "");
   virtual IPCClientInterface *NewClient(const std::string &name) = 0;
 };
@@ -194,11 +194,11 @@ class IPCClientFactory : public IPCClientFactoryInterface {
  public:
   ~IPCClientFactory() override;
 
-  // new inteface
+  // new interface
   IPCClientInterface *NewClient(const std::string &name,
                                 const std::string &path_name) override;
 
-  // old interface for backward compatiblity.
+  // old interface for backward compatibility.
   // same as NewClient(name, "");
   IPCClientInterface *NewClient(const std::string &name) override;
 
@@ -232,7 +232,7 @@ class IPCServer {
   IPCServer(const std::string &name, int32 num_connections, int32 timeout);
   virtual ~IPCServer();
 
-  // Return true if the connectoin is available
+  // Return true if the connection is available
   bool Connected() const;
 
   // Implement a server algorithm in subclass.
diff --git ipc/ipc_main.cc ipc/ipc_main.cc
index dc81d5eec..60df8b319 100644
--- ipc/ipc_main.cc
+++ ipc/ipc_main.cc
@@ -32,20 +32,20 @@
 #include <string>
 #include <vector>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/port.h"
 #include "base/thread.h"
 #include "ipc/ipc.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, server_address, "ipc_test", "");
-MOZC_FLAG(bool, test, false, "automatic test mode");
-MOZC_FLAG(bool, server, false, "invoke as server mode");
-MOZC_FLAG(bool, client, false, "invoke as client mode");
-MOZC_FLAG(string, server_path, "", "server path");
-MOZC_FLAG(int32, num_threads, 10, "number of threads");
-MOZC_FLAG(int32, num_requests, 100, "number of requests");
+ABSL_FLAG(std::string, server_address, "ipc_test", "");
+ABSL_FLAG(bool, test, false, "automatic test mode");
+ABSL_FLAG(bool, server, false, "invoke as server mode");
+ABSL_FLAG(bool, client, false, "invoke as client mode");
+ABSL_FLAG(std::string, server_path, "", "server path");
+ABSL_FLAG(int32, num_threads, 10, "number of threads");
+ABSL_FLAG(int32, num_requests, 100, "number of requests");
 
 namespace mozc {
 
@@ -53,9 +53,9 @@ class MultiConnections : public Thread {
  public:
   void Run() {
     char buf[8192];
-    for (int i = 0; i < mozc::GetFlag(FLAGS_num_requests); ++i) {
+    for (int i = 0; i < absl::GetFlag(FLAGS_num_requests); ++i) {
       mozc::IPCClient con(FLAGS_server_address,
-                          mozc::GetFlag(FLAGS_server_path));
+                          absl::GetFlag(FLAGS_server_path));
       CHECK(con.Connected());
       string input = "testtesttesttest";
       size_t length = sizeof(buf);
@@ -94,13 +94,13 @@ class EchoServerThread : public Thread {
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
-  if (mozc::GetFlag(FLAGS_test)) {
-    mozc::EchoServer con(mozc::GetFlag(FLAGS_server_address), 10, 1000);
+  if (absl::GetFlag(FLAGS_test)) {
+    mozc::EchoServer con(absl::GetFlag(FLAGS_server_address), 10, 1000);
     mozc::EchoServerThread server_thread_main(&con);
     server_thread_main.SetJoinable(true);
     server_thread_main.Start("IpcMain");
 
-    std::vector<mozc::MultiConnections> cons(mozc::GetFlag(FLAGS_num_threads));
+    std::vector<mozc::MultiConnections> cons(absl::GetFlag(FLAGS_num_threads));
     for (size_t i = 0; i < cons.size(); ++i) {
       cons[i].SetJoinable(true);
       cons[i].Start("MultiConnections");
@@ -110,7 +110,7 @@ int main(int argc, char **argv) {
     }
 
     mozc::IPCClient kill(FLAGS_server_address,
-                         mozc::GetFlag(FLAGS_server_path));
+                         absl::GetFlag(FLAGS_server_path));
     const char kill_cmd[32] = "kill";
     char output[32];
     size_t output_size = sizeof(output);
@@ -119,17 +119,17 @@ int main(int argc, char **argv) {
 
     LOG(INFO) << "Done";
 
-  } else if (mozc::GetFlag(FLAGS_server)) {
-    mozc::EchoServer con(mozc::GetFlag(FLAGS_server_address), 10, -1);
+  } else if (absl::GetFlag(FLAGS_server)) {
+    mozc::EchoServer con(absl::GetFlag(FLAGS_server_address), 10, -1);
     CHECK(con.Connected());
-    LOG(INFO) << "Start Server at " << mozc::GetFlag(FLAGS_server_address);
+    LOG(INFO) << "Start Server at " << absl::GetFlag(FLAGS_server_address);
     con.Loop();
-  } else if (mozc::GetFlag(FLAGS_client)) {
+  } else if (absl::GetFlag(FLAGS_client)) {
     string line;
     char response[8192];
     while (getline(cin, line)) {
       mozc::IPCClient con(FLAGS_server_address,
-                          mozc::GetFlag(FLAGS_server_path));
+                          absl::GetFlag(FLAGS_server_path));
       CHECK(con.Connected());
       size_t response_size = sizeof(response);
       CHECK(con.Call(line.data(), line.size(), response, &response_size, 1000));
diff --git ipc/ipc_path_manager_main.cc ipc/ipc_path_manager_main.cc
index 3317a812c..8fdf64985 100644
--- ipc/ipc_path_manager_main.cc
+++ ipc/ipc_path_manager_main.cc
@@ -29,34 +29,34 @@
 
 #include <string>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/port.h"
 #include "base/util.h"
 #include "ipc/ipc_path_manager.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(bool, client, false, "client mode");
-MOZC_FLAG(bool, server, false, "server mode");
-MOZC_FLAG(string, name, "test", "ipc name");
+ABSL_FLAG(bool, client, false, "client mode");
+ABSL_FLAG(bool, server, false, "server mode");
+ABSL_FLAG(std::string, name, "test", "ipc name");
 
 // command line tool to check the behavior of IPCPathManager
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
   mozc::IPCPathManager *manager =
-      mozc::IPCPathManager::GetIPCPathManager(mozc::GetFlag(FLAGS_name));
+      mozc::IPCPathManager::GetIPCPathManager(absl::GetFlag(FLAGS_name));
   CHECK(manager);
 
   string path;
 
-  if (mozc::GetFlag(FLAGS_client)) {
+  if (absl::GetFlag(FLAGS_client)) {
     CHECK(manager->GetPathName(&path));
     LOG(INFO) << "PathName: " << path;
     return 0;
   }
 
-  if (mozc::GetFlag(FLAGS_server)) {
+  if (absl::GetFlag(FLAGS_server)) {
     CHECK(manager->CreateNewPathName());
     CHECK(manager->SavePathName());
     CHECK(manager->GetPathName(&path));
diff --git ipc/ipc_path_manager_test.cc ipc/ipc_path_manager_test.cc
index 466bec00f..46f429094 100644
--- ipc/ipc_path_manager_test.cc
+++ ipc/ipc_path_manager_test.cc
@@ -38,7 +38,6 @@
 
 #include "base/file_stream.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/port.h"
 #include "base/process_mutex.h"
 #include "base/system_util.h"
@@ -49,6 +48,7 @@
 #include "ipc/ipc.pb.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace {
@@ -87,7 +87,7 @@ class BatchGetPathNameThread : public Thread {
 class IPCPathManagerTest : public ::testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   }
 };
 
diff --git ipc/ipc_test.cc ipc/ipc_test.cc
index a5ed6be6a..25f6c2b40 100644
--- ipc/ipc_test.cc
+++ ipc/ipc_test.cc
@@ -32,7 +32,6 @@
 #include <algorithm>
 #include <vector>
 
-#include "base/flags.h"
 #include "base/port.h"
 #include "base/system_util.h"
 #include "base/thread.h"
@@ -40,6 +39,7 @@
 #include "ipc/ipc_test_util.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace {
 
@@ -117,7 +117,7 @@ class EchoServer : public mozc::IPCServer {
 }  // namespace
 
 TEST(IPCTest, IPCTest) {
-  mozc::SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+  mozc::SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
 #ifdef __APPLE__
   mozc::TestMachPortManager manager;
 #endif
diff --git ipc/named_event.h ipc/named_event.h
index 5985c4f0b..77959dc8a 100644
--- ipc/named_event.h
+++ ipc/named_event.h
@@ -47,7 +47,7 @@
 // Example:
 //
 // (Process 1)
-// NamedEventListener listner("foo");   // Create named event listener named foo
+// NamedEventListener listener("foo");  // Create named event listener named foo
 // CHECK(listener.IsAvailable());
 // listener.Wait(10000);  // Wait until an event comes.
 // Access shared resource
@@ -107,8 +107,8 @@ class NamedEventListener {
   // Return true if NamedEventListener is available
   bool IsAvailable() const;
 
-  // return true if NamedEventListner is created by this instance.
-  // If NamedEventListner opened an exiting handle, return false.
+  // return true if NamedEventListener is created by this instance.
+  // If NamedEventListener opened an exiting handle, return false.
   bool IsOwner() const;
 
   // Wait until the listener receives a notification
@@ -118,7 +118,7 @@ class NamedEventListener {
   bool Wait(int msec);
 
   // Wait until the listener receives a notification or
-  // the process specfied with pid is terminated.
+  // the process specified with pid is terminated.
   // return TIMEOUT: reached timeout
   // return EVENT_SIGNALED: event is signaled.
   // return PROCESS_SIGNALED: process is signaled.
diff --git ipc/named_event_main.cc ipc/named_event_main.cc
index bf95251a9..02d87d0de 100644
--- ipc/named_event_main.cc
+++ ipc/named_event_main.cc
@@ -29,39 +29,39 @@
 
 #include <string>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/port.h"
 #include "ipc/named_event.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(bool, listener, true, "listener mode");
-MOZC_FLAG(bool, notifier, false, "notifier mode");
-MOZC_FLAG(int32, timeout, -1, "timeout (msec)");
-MOZC_FLAG(int32, pid, -1, "process id");
-MOZC_FLAG(string, name, "named_event_test", "name for named event");
+ABSL_FLAG(bool, listener, true, "listener mode");
+ABSL_FLAG(bool, notifier, false, "notifier mode");
+ABSL_FLAG(int32, timeout, -1, "timeout (msec)");
+ABSL_FLAG(int32, pid, -1, "process id");
+ABSL_FLAG(std::string, name, "named_event_test", "name for named event");
 
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
-  if (mozc::GetFlag(FLAGS_notifier)) {
-    mozc::NamedEventNotifier notifier(mozc::GetFlag(FLAGS_name).c_str());
+  if (absl::GetFlag(FLAGS_notifier)) {
+    mozc::NamedEventNotifier notifier(absl::GetFlag(FLAGS_name).c_str());
     CHECK(notifier.IsAvailable()) << "NamedEventNotifier is not available";
 
     notifier.Notify();
     LOG(INFO) << "Notification has been sent";
 
-  } else if (mozc::GetFlag(FLAGS_listener)) {
-    mozc::NamedEventListener listener(mozc::GetFlag(FLAGS_name).c_str());
+  } else if (absl::GetFlag(FLAGS_listener)) {
+    mozc::NamedEventListener listener(absl::GetFlag(FLAGS_name).c_str());
     CHECK(listener.IsAvailable()) << "NamedEventListener is not available";
 
     LOG_IF(INFO, listener.IsOwner()) << "This instance owns event handle";
 
-    LOG(INFO) << "Waiting event " << mozc::GetFlag(FLAGS_name);
-    if (mozc::GetFlag(FLAGS_pid) != -1) {
+    LOG(INFO) << "Waiting event " << absl::GetFlag(FLAGS_name);
+    if (absl::GetFlag(FLAGS_pid) != -1) {
       switch (listener.WaitEventOrProcess(
-          mozc::GetFlag(FLAGS_timeout),
-          static_cast<size_t>(mozc::GetFlag(FLAGS_pid)))) {
+          absl::GetFlag(FLAGS_timeout),
+          static_cast<size_t>(absl::GetFlag(FLAGS_pid)))) {
         case mozc::NamedEventListener::TIMEOUT:
           LOG(INFO) << "timeout";
           break;
@@ -76,7 +76,7 @@ int main(int argc, char **argv) {
           break;
       }
     } else {
-      if (listener.Wait(mozc::GetFlag(FLAGS_timeout))) {
+      if (listener.Wait(absl::GetFlag(FLAGS_timeout))) {
         LOG(INFO) << "Event comes";
       }
     }
diff --git ipc/named_event_test.cc ipc/named_event_test.cc
index aa7c629f6..a64ea8138 100644
--- ipc/named_event_test.cc
+++ ipc/named_event_test.cc
@@ -34,13 +34,13 @@
 #include <string>
 
 #include "base/clock.h"
-#include "base/flags.h"
 #include "base/port.h"
 #include "base/system_util.h"
 #include "base/thread.h"
 #include "base/util.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 namespace mozc {
@@ -87,7 +87,7 @@ class NamedEventListenerThread : public Thread {
 class NamedEventTest : public testing::Test {
   void SetUp() override {
     original_user_profile_directory_ = SystemUtil::GetUserProfileDirectory();
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   }
 
   void TearDown() override {
diff --git ipc/process_watch_dog_main.cc ipc/process_watch_dog_main.cc
index ee0ef0739..691c75114 100644
--- ipc/process_watch_dog_main.cc
+++ ipc/process_watch_dog_main.cc
@@ -31,15 +31,15 @@
 #include <string>
 #include <vector>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/number_util.h"
 #include "base/port.h"
 #include "base/util.h"
 #include "ipc/process_watch_dog.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(int32, timeout, -1, "set timeout");
+ABSL_FLAG(int32, timeout, -1, "set timeout");
 
 namespace mozc {
 class TestProcessWatchDog : public ProcessWatchDog {
@@ -75,7 +75,7 @@ int main(int argc, char **argv) {
 
     if (!dog.SetID(static_cast<mozc::ProcessWatchDog::ProcessID>(process_id),
                    static_cast<mozc::ProcessWatchDog::ThreadID>(thread_id),
-                   mozc::GetFlag(FLAGS_timeout))) {
+                   absl::GetFlag(FLAGS_timeout))) {
       std::cout << "Error" << std::endl;
     } else {
       std::cout << "OK" << std::endl;
diff --git ipc/win32_ipc.cc ipc/win32_ipc.cc
index c6f9fc889..d954a0f04 100644
--- ipc/win32_ipc.cc
+++ ipc/win32_ipc.cc
@@ -554,7 +554,7 @@ void IPCServer::Loop() {
                                       INFINITE, &overlapped, &ignored,
                                       &ipc_error, kReadTypeData)) {
           if (ipc_error == IPC_QUIT_EVENT_SIGNALED) {
-            VLOG(1) << "Recived Conrol event from other thread";
+            VLOG(1) << "Received Conrol event from other thread";
             connected_ = false;
             return;
           }
@@ -614,7 +614,7 @@ void IPCServer::Loop() {
     if (!RecvIPCMessage(pipe_handle_.get(), pipe_event_.get(), ack_request,
                         &ack_request_size, kAckTimeout, kReadTypeACK,
                         &last_ipc_error)) {
-      // This case happens when the client did not recive the server's response
+      // This case happens when the client did not receive the server's response
       // within timeout. Anyway we will close the connection so that the server
       // will not be blocked.
       LOG(WARNING) << "Client didn't respond within " << kAckTimeout
diff --git mac/BUILD mac/BUILD
index 5151898ff..54ee9ec39 100644
--- mac/BUILD
+++ mac/BUILD
@@ -28,11 +28,156 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-load("//:build_defs.bzl", "objc_library_mozc")
+load(
+    "//:build_defs.bzl",
+    "info_plist_mozc",
+    "macos_application_mozc",
+    "objc_library_mozc",
+    "py_binary_mozc",
+)
+load(
+    "//:config.bzl",
+    "BRANDING",
+    "MACOS_BUNDLE_ID_PREFIX",
+)
 
 package(default_visibility = ["//:__subpackages__"])
 
+macos_application_mozc(
+    name = "mozc_macos",
+    app_icons = ["//data/images/mac:product_icon.icns"],
+    bundle_id = MACOS_BUNDLE_ID_PREFIX,
+    bundle_name = BRANDING,
+    infoplists = [":info_plist"],
+    resources = [
+        "//data/images/mac:direct.tiff",
+        "//data/images/mac:full_ascii.tiff",
+        "//data/images/mac:full_katakana.tiff",
+        "//data/images/mac:half_ascii.tiff",
+        "//data/images/mac:half_katakana.tiff",
+        "//data/images/mac:hiragana.tiff",
+        "//data/installer:credits_en.html",
+    ],
+    deps = ["mozc_macos_main_lib"],
+)
+
 objc_library_mozc(
     name = "common",
     hdrs = ["common.h"],
 )
+
+objc_library_mozc(
+    name = "mozc_macos_main_lib",
+    srcs = ["main.mm"],
+    sdk_frameworks = ["InputMethodKit"],
+    deps = [
+        ":imk_controller",
+        ":imk_server",
+        "//base:crash_report_handler",
+        "//base:init_mozc",
+        "//base:logging",
+        "//base:run_level",
+        "//client",
+        "//config:stats_config_util",
+    ],
+)
+
+objc_library_mozc(
+    name = "imk_controller",
+    srcs = [
+        "GoogleJapaneseInputController.mm",
+    ],
+    hdrs = [
+        "GoogleJapaneseInputController.h",
+    ],
+    proto_deps = [
+        "//protocol:commands_proto",
+        "//protocol:config_proto",
+        "//protocol:renderer_proto",
+    ],
+    textual_hdrs = [
+        "GoogleJapaneseInputControllerInterface.h",
+    ],
+    deps = [
+        ":common",
+        ":imk_server",
+        ":keycode_map",
+        "//base:logging",
+        "//base:mac_process",
+        "//base:mac_util",
+        "//base:mutex",
+        "//base:util",
+        "//client",
+        "//ipc",
+        "//renderer:renderer_client",
+        "//session:ime_switch_util",
+    ],
+)
+
+objc_library_mozc(
+    name = "imk_server",
+    srcs = ["GoogleJapaneseInputServer.mm"],
+    hdrs = ["GoogleJapaneseInputServer.h"],
+    proto_deps = ["//protocol:commands_proto"],
+    deps = [
+        ":common",
+        "//base:logging",
+        "//base:mutex",
+    ],
+)
+
+objc_library_mozc(
+    name = "keycode_map",
+    srcs = ["KeyCodeMap.mm"],
+    hdrs = ["KeyCodeMap.h"],
+    proto_deps = ["//protocol:commands_proto"],
+    textual_hdrs = [
+        ":init_kanamap",
+        ":init_specialkeymap",
+        ":init_specialcharmap",
+    ],
+    deps = [
+        "//base:logging",
+        "//base:mutex",
+    ],
+)
+
+py_binary_mozc(
+    name = "generate_mapping",
+    srcs = ["generate_mapping.py"],
+    deps = [],
+)
+
+genrule(
+    name = "init_kanamap",
+    srcs = ["//data/preedit:mac-kana.tsv"],
+    outs = ["init_kanamap.h"],
+    cmd = ("$(location :generate_mapping) --mapname=KanaMap" +
+           " --result_type='const char *' --filename $< > $@"),
+    exec_tools = [":generate_mapping"],
+)
+
+genrule(
+    name = "init_specialkeymap",
+    srcs = ["//data/preedit:mac-specialkeys.tsv"],
+    outs = ["init_specialkeymap.h"],
+    cmd = ("$(location :generate_mapping) --mapname=SpecialKeyMap" +
+           " --result_type=KeyEvent::SpecialKey --filename $< > $@"),
+    exec_tools = [":generate_mapping"],
+)
+
+genrule(
+    name = "init_specialcharmap",
+    srcs = ["//data/preedit:mac-specialchars.tsv"],
+    outs = ["init_specialcharmap.h"],
+    cmd = ("$(location :generate_mapping) --mapname=SpecialCharMap" +
+           " --key_type=unichar --result_type=KeyEvent::SpecialKey" +
+           " --filename $< > $@"),
+    exec_tools = [":generate_mapping"],
+)
+
+info_plist_mozc(
+    name = "info_plist",
+    srcs = ["Info.plist"],
+    outs = [BRANDING + "Info.plist"],
+)
diff --git mac/GoogleJapaneseInputControllerInterface.h mac/GoogleJapaneseInputControllerInterface.h
index 62c9a5a8d..7d811ec0b 100644
--- mac/GoogleJapaneseInputControllerInterface.h
+++ mac/GoogleJapaneseInputControllerInterface.h
@@ -80,7 +80,7 @@
 
 // Set up the client capability
 - (void)setupCapability;
-// Set up the cilent bundle for the sender.
+// Set up the client bundle for the sender.
 - (void)setupClientBundle:(id)sender;
 
 // Launch the word register tool with the current selection range.
diff --git mac/GoogleJapaneseInputServer.mm mac/GoogleJapaneseInputServer.mm
index 4a668144e..041c6fa8b 100644
--- mac/GoogleJapaneseInputServer.mm
+++ mac/GoogleJapaneseInputServer.mm
@@ -29,8 +29,6 @@
 
 #import "mac/GoogleJapaneseInputServer.h"
 
-#import "mac/GoogleJapaneseInputController.h"
-
 #include <string>
 
 #include "base/const.h"
diff --git mac/Uninstaller/Uninstaller_main.mm mac/Uninstaller/Uninstaller_main.mm
index 4e4cd15b1..5d808ac9b 100644
--- mac/Uninstaller/Uninstaller_main.mm
+++ mac/Uninstaller/Uninstaller_main.mm
@@ -32,8 +32,8 @@
 #import "DialogsController.h"
 #import "Uninstaller.h"
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
+#include "absl/flags/flag.h"
 
 int main(int argc, char *argv[]) {
   mozc::InitMozc(argv[0], &argc, &argv);
diff --git mac/main.mm mac/main.mm
index c53be5fd3..a16eeb391 100644
--- mac/main.mm
+++ mac/main.mm
@@ -38,12 +38,12 @@
 
 #include "base/const.h"
 #include "base/crash_report_handler.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/run_level.h"
 #include "client/client.h"
 #include "config/stats_config_util.h"
+#include "absl/flags/flag.h"
 
 int main(int argc, char *argv[]) {
   if (!mozc::RunLevel::IsValidClientRunLevel()) {
diff --git prediction/BUILD prediction/BUILD
index de816004f..e4afa4f2f 100644
--- prediction/BUILD
+++ prediction/BUILD
@@ -77,7 +77,6 @@ cc_library_mozc(
         "//base",
         "//base:clock",
         "//base:config_file_stream",
-        "//base:flags",
         "//base:freelist",
         "//base:hash",
         "//base:logging",
@@ -99,6 +98,7 @@ cc_library_mozc(
         "//storage:lru_cache",
         "//testing:gunit_prod",
         "//usage_stats",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
         "@com_google_absl//absl/strings",
     ],
@@ -117,7 +117,6 @@ cc_test_mozc(
         "//base:clock_mock",
         "//base:encryptor",
         "//base:file_util",
-        "//base:flags",
         "//base:logging",
         "//base:port",
         "//base:system_util",
@@ -137,6 +136,7 @@ cc_test_mozc(
         "//testing:gunit_main",
         "//usage_stats",
         "//usage_stats:usage_stats_testing_util",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
         "@com_google_absl//absl/strings",
     ],
@@ -153,7 +153,6 @@ cc_library_mozc(
         ":suggestion_filter",
         ":zero_query_dict",
         "//base",
-        "//base:flags",
         "//base:logging",
         "//base:mozc_hash_map",
         "//base:number_util",
@@ -176,6 +175,7 @@ cc_library_mozc(
         "//request:conversion_request",
         "//testing:gunit_prod",
         "//usage_stats",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
     alwayslink = 1,
@@ -194,7 +194,6 @@ cc_test_mozc(
         ":suggestion_filter",
         ":zero_query_dict",
         "//base",
-        "//base:flags",
         "//base:logging",
         "//base:port",
         "//base:serialized_string_array",
@@ -230,6 +229,7 @@ cc_test_mozc(
         "//transliteration",
         "//usage_stats",
         "//usage_stats:usage_stats_testing_util",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
         "@com_google_absl//absl/strings",
     ],
@@ -242,13 +242,13 @@ cc_library_mozc(
     deps = [
         ":predictor_interface",
         "//base",
-        "//base:flags",
         "//base:logging",
         "//config:config_handler",
         "//converter:segments",
         "//protocol:commands_proto",
         "//protocol:config_proto",
         "//request:conversion_request",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
     alwayslink = 1,
@@ -330,12 +330,12 @@ cc_binary_mozc(
         "//base",
         "//base:codegen_bytearray_stream",
         "//base:file_stream",
-        "//base:flags",
         "//base:hash",
         "//base:init_mozc_buildtool",
         "//base:logging",
         "//base:util",
         "//storage:existence_filter",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
diff --git prediction/dictionary_predictor.cc prediction/dictionary_predictor.cc
index c3158b41b..8dd70a92a 100644
--- prediction/dictionary_predictor.cc
+++ prediction/dictionary_predictor.cc
@@ -40,7 +40,6 @@
 #include <utility>
 #include <vector>
 
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/mozc_hash_map.h"
 #include "base/number_util.h"
@@ -61,6 +60,7 @@
 #include "protocol/config.pb.h"
 #include "request/conversion_request.h"
 #include "usage_stats/usage_stats.h"
+#include "absl/flags/flag.h"
 #include "absl/strings/string_view.h"
 
 #ifndef NDEBUG
@@ -233,7 +233,7 @@ class DictionaryPredictor::PredictiveLookupCallback
     // If the token is from user dictionary and its POS is unknown, it is
     // suggest-only words.  Such words are looked up only when their keys
     // exactly match |key|.  Otherwise, unigram suggestion can be annoying.  For
-    // example, suppose a user registers his/her email address as める.  Then,
+    // example, suppose a user registers their email address as める.  Then,
     // we don't want to show the email address from め but exactly from める.
     if ((token.attributes & Token::USER_DICTIONARY) != 0 &&
         token.lid == unknown_id_) {
diff --git prediction/dictionary_predictor_test.cc prediction/dictionary_predictor_test.cc
index 5d62e295c..d550d9630 100644
--- prediction/dictionary_predictor_test.cc
+++ prediction/dictionary_predictor_test.cc
@@ -37,7 +37,6 @@
 #include <utility>
 #include <vector>
 
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/port.h"
 #include "base/serialized_string_array.h"
@@ -76,6 +75,7 @@
 #include "transliteration/transliteration.h"
 #include "usage_stats/usage_stats.h"
 #include "usage_stats/usage_stats_testing_util.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 #include "absl/strings/string_view.h"
 
@@ -362,7 +362,7 @@ class MockTypingModel : public mozc::composer::TypingModel {
 class DictionaryPredictorTest : public ::testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     request_ = absl::make_unique<commands::Request>();
     config_ = absl::make_unique<config::Config>();
     config::ConfigHandler::GetDefaultConfig(config_.get());
@@ -2837,42 +2837,42 @@ TEST_F(DictionaryPredictorTest, SetLMCostForUserDictionaryWord) {
 
   {
     // Cost of words in user dictionary should be decreased.
-    const int kOrigianlWordCost = 10000;
+    const int kOriginalWordCost = 10000;
     std::vector<TestableDictionaryPredictor::Result> results;
     AddTestableDictionaryPredictorResult(
-        kAikaHiragana, kAikaKanji, kOrigianlWordCost,
+        kAikaHiragana, kAikaKanji, kOriginalWordCost,
         TestableDictionaryPredictor::UNIGRAM, Token::USER_DICTIONARY, &results);
 
     predictor->SetLMCost(segments, &results);
 
     EXPECT_EQ(1, results.size());
     EXPECT_EQ(kAikaKanji, results[0].value);
-    EXPECT_GT(kOrigianlWordCost, results[0].cost);
+    EXPECT_GT(kOriginalWordCost, results[0].cost);
     EXPECT_LE(1, results[0].cost);
   }
 
   {
     // Cost of words in user dictionary should not be decreased to below 1.
-    const int kOrigianlWordCost = 10;
+    const int kOriginalWordCost = 10;
     std::vector<TestableDictionaryPredictor::Result> results;
     AddTestableDictionaryPredictorResult(
-        kAikaHiragana, kAikaKanji, kOrigianlWordCost,
+        kAikaHiragana, kAikaKanji, kOriginalWordCost,
         TestableDictionaryPredictor::UNIGRAM, Token::USER_DICTIONARY, &results);
 
     predictor->SetLMCost(segments, &results);
 
     EXPECT_EQ(1, results.size());
     EXPECT_EQ(kAikaKanji, results[0].value);
-    EXPECT_GT(kOrigianlWordCost, results[0].cost);
+    EXPECT_GT(kOriginalWordCost, results[0].cost);
     EXPECT_LE(1, results[0].cost);
   }
 
   {
     // Cost of general symbols should not be decreased.
-    const int kOrigianlWordCost = 10000;
+    const int kOriginalWordCost = 10000;
     std::vector<TestableDictionaryPredictor::Result> results;
     AddTestableDictionaryPredictorResult(
-        kAikaHiragana, kAikaKanji, kOrigianlWordCost,
+        kAikaHiragana, kAikaKanji, kOriginalWordCost,
         TestableDictionaryPredictor::UNIGRAM, Token::USER_DICTIONARY, &results);
     ASSERT_EQ(1, results.size());
     results[0].lid = data_and_predictor->pos_matcher().GetGeneralSymbolId();
@@ -2881,22 +2881,22 @@ TEST_F(DictionaryPredictorTest, SetLMCostForUserDictionaryWord) {
 
     EXPECT_EQ(1, results.size());
     EXPECT_EQ(kAikaKanji, results[0].value);
-    EXPECT_LE(kOrigianlWordCost, results[0].cost);
+    EXPECT_LE(kOriginalWordCost, results[0].cost);
   }
 
   {
     // Cost of words not in user dictionary should not be decreased.
-    const int kOrigianlWordCost = 10000;
+    const int kOriginalWordCost = 10000;
     std::vector<TestableDictionaryPredictor::Result> results;
     AddTestableDictionaryPredictorResult(
-        kAikaHiragana, kAikaKanji, kOrigianlWordCost,
+        kAikaHiragana, kAikaKanji, kOriginalWordCost,
         TestableDictionaryPredictor::UNIGRAM, Token::NONE, &results);
 
     predictor->SetLMCost(segments, &results);
 
     EXPECT_EQ(1, results.size());
     EXPECT_EQ(kAikaKanji, results[0].value);
-    EXPECT_EQ(kOrigianlWordCost, results[0].cost);
+    EXPECT_EQ(kOriginalWordCost, results[0].cost);
   }
 }
 
diff --git prediction/gen_suggestion_filter_main.cc prediction/gen_suggestion_filter_main.cc
index bff0d615d..264e6d57c 100644
--- prediction/gen_suggestion_filter_main.cc
+++ prediction/gen_suggestion_filter_main.cc
@@ -33,17 +33,17 @@
 
 #include "base/codegen_bytearray_stream.h"
 #include "base/file_stream.h"
-#include "base/flags.h"
 #include "base/hash.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/util.h"
 #include "storage/existence_filter.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, input, "", "per-line suggestion filter list");
-MOZC_FLAG(string, output, "", "output bloom filter");
-MOZC_FLAG(bool, header, true, "make header file instead of raw bloom filter");
-MOZC_FLAG(string, name, "SuggestionFilterData",
+ABSL_FLAG(std::string, input, "", "per-line suggestion filter list");
+ABSL_FLAG(std::string, output, "", "output bloom filter");
+ABSL_FLAG(bool, header, true, "make header file instead of raw bloom filter");
+ABSL_FLAG(std::string, name, "SuggestionFilterData",
           "name for variable name in the header file");
 
 namespace {
@@ -70,15 +70,15 @@ using mozc::storage::ExistenceFilter;
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
-  if ((mozc::GetFlag(FLAGS_input).empty() ||
-       mozc::GetFlag(FLAGS_output).empty()) && argc > 2) {
-    mozc::SetFlag(&FLAGS_input, argv[1]);
-    mozc::SetFlag(&FLAGS_output, argv[2]);
+  if ((absl::GetFlag(FLAGS_input).empty() ||
+       absl::GetFlag(FLAGS_output).empty()) && argc > 2) {
+    absl::SetFlag(&FLAGS_input, argv[1]);
+    absl::SetFlag(&FLAGS_output, argv[2]);
   }
 
   std::vector<uint64> words;
 
-  ReadWords(mozc::GetFlag(FLAGS_input), &words);
+  ReadWords(absl::GetFlag(FLAGS_input), &words);
 
   LOG(INFO) << words.size() << " words found";
 
@@ -99,19 +99,19 @@ int main(int argc, char **argv) {
   char *buf = nullptr;
   size_t size = 0;
 
-  LOG(INFO) << "writing bloomfilter: " << mozc::GetFlag(FLAGS_output);
+  LOG(INFO) << "writing bloomfilter: " << absl::GetFlag(FLAGS_output);
   filter->Write(&buf, &size);
 
-  if (mozc::GetFlag(FLAGS_header)) {
-    mozc::OutputFileStream ofs(mozc::GetFlag(FLAGS_output).c_str());
+  if (absl::GetFlag(FLAGS_header)) {
+    mozc::OutputFileStream ofs(absl::GetFlag(FLAGS_output).c_str());
     mozc::CodeGenByteArrayOutputStream codegen_stream(
         &ofs, mozc::codegenstream::NOT_OWN_STREAM);
-    codegen_stream.OpenVarDef(mozc::GetFlag(FLAGS_name));
+    codegen_stream.OpenVarDef(absl::GetFlag(FLAGS_name));
     codegen_stream.write(buf, size);
     codegen_stream.CloseVarDef();
   } else {
     mozc::OutputFileStream ofs(
-        mozc::GetFlag(FLAGS_output).c_str(),
+        absl::GetFlag(FLAGS_output).c_str(),
         std::ios::out | std::ios::trunc | std::ios::binary);
     ofs.write(buf, size);
   }
diff --git prediction/predictor.cc prediction/predictor.cc
index 3937dc836..b7c0e8e28 100644
--- prediction/predictor.cc
+++ prediction/predictor.cc
@@ -34,11 +34,11 @@
 #include <utility>
 #include <vector>
 
-#include "base/flags.h"
 #include "base/logging.h"
 #include "converter/segments.h"
 #include "protocol/commands.pb.h"
 #include "protocol/config.pb.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 namespace mozc {
diff --git prediction/predictor_test.cc prediction/predictor_test.cc
index 702b48d5e..de65565fd 100644
--- prediction/predictor_test.cc
+++ prediction/predictor_test.cc
@@ -202,7 +202,7 @@ TEST_F(MobilePredictorTest, CallPredictorsForMobilePartialPrediction) {
   EXPECT_TRUE(predictor->PredictForRequest(*convreq_, &segments));
 }
 
-TEST_F(MobilePredictorTest, CallPredictForRequetMobile) {
+TEST_F(MobilePredictorTest, CallPredictForRequestMobile) {
   auto predictor1 = absl::make_unique<MockPredictor>();
   auto predictor2 = absl::make_unique<MockPredictor>();
   EXPECT_CALL(*predictor1, PredictForRequest(_, _))
@@ -310,7 +310,7 @@ TEST_F(PredictorTest, CallPredictorsForPrediction) {
   EXPECT_TRUE(predictor->PredictForRequest(*convreq_, &segments));
 }
 
-TEST_F(PredictorTest, CallPredictForRequet) {
+TEST_F(PredictorTest, CallPredictForRequest) {
   auto predictor1 = absl::make_unique<MockPredictor>();
   auto predictor2 = absl::make_unique<MockPredictor>();
   EXPECT_CALL(*predictor1, PredictForRequest(_, _))
diff --git prediction/user_history_predictor.cc prediction/user_history_predictor.cc
index 4d5b64847..9c6712965 100644
--- prediction/user_history_predictor.cc
+++ prediction/user_history_predictor.cc
@@ -38,7 +38,6 @@
 
 #include "base/clock.h"
 #include "base/config_file_stream.h"
-#include "base/flags.h"
 #include "base/hash.h"
 #include "base/logging.h"
 #include "base/mozc_hash_set.h"
@@ -59,6 +58,7 @@
 #include "storage/encrypted_string_storage.h"
 #include "storage/lru_cache.h"
 #include "usage_stats/usage_stats.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 namespace mozc {
@@ -241,7 +241,7 @@ bool UserHistoryStorage::Load() {
       << num_deleted << " old entries were not loaded "
       << proto_.entries_size();
 
-  VLOG(1) << "Loaded user histroy, size=" << proto_.entries_size();
+  VLOG(1) << "Loaded user history, size=" << proto_.entries_size();
   return true;
 }
 
@@ -473,7 +473,7 @@ bool UserHistoryPredictor::Load(const UserHistoryStorage &history) {
                  history.GetProto().entries(i));
   }
 
-  VLOG(1) << "Loaded user histroy, size=" << history.GetProto().entries_size();
+  VLOG(1) << "Loaded user history, size=" << history.GetProto().entries_size();
 
   return true;
 }
diff --git prediction/user_history_predictor_test.cc prediction/user_history_predictor_test.cc
index 71e56c912..ef2f0bab6 100644
--- prediction/user_history_predictor_test.cc
+++ prediction/user_history_predictor_test.cc
@@ -35,7 +35,6 @@
 
 #include "base/clock_mock.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/password_manager.h"
 #include "base/port.h"
@@ -57,6 +56,7 @@
 #include "testing/base/public/gunit.h"
 #include "usage_stats/usage_stats.h"
 #include "usage_stats/usage_stats_testing_util.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 #include "absl/strings/string_view.h"
 
@@ -207,7 +207,7 @@ bool FindCandidateByValue(const std::string &value, const Segments &segments) {
 class UserHistoryPredictorTest : public ::testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     request_ = absl::make_unique<Request>();
     config_ = absl::make_unique<Config>();
     config::ConfigHandler::GetDefaultConfig(config_.get());
@@ -926,7 +926,7 @@ TEST_F(UserHistoryPredictorTest, HistoryToPunctuation) {
 
   Segments segments;
 
-  // Scenario 1: A user have commited "亜" by prediction and then commit "。".
+  // Scenario 1: A user have committed "亜" by prediction and then commit "。".
   // Then, the unigram "亜" is learned but the bigram "亜。" shouldn't.
   SetUpInputForPrediction("あ", composer_.get(), &segments);
   AddCandidate(0, "亜", &segments);
@@ -979,7 +979,7 @@ TEST_F(UserHistoryPredictorTest, HistoryToPunctuation) {
   EXPECT_EQ("お疲れ様です。", segments.segment(0).candidate(1).value);
 }
 
-TEST_F(UserHistoryPredictorTest, UserHistoryPredictorPreceedingPunctuation) {
+TEST_F(UserHistoryPredictorTest, UserHistoryPredictorPrecedingPunctuation) {
   UserHistoryPredictor *predictor = GetUserHistoryPredictorWithClearedHistory();
 
   Segments segments;
@@ -2002,7 +2002,7 @@ const bool kNonSensitive = false;
 
 const PrivacySensitiveTestData kNonSensitiveCases[] = {
     {kNonSensitive,  // We might want to revisit this behavior
-     "Type privacy sensitive number but it is commited as full-width number "
+     "Type privacy sensitive number but it is committed as full-width number "
      "by mistake.",
      "0007", "０００７"},
     {kNonSensitive, "Type a ZIP number.", "100-0001", "東京都千代田区千代田"},
@@ -2237,7 +2237,7 @@ TEST_F(UserHistoryPredictorTest, UserHistoryStorageContainingOldEntries) {
   // Test Load().
   {
     const std::string filename =
-        FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "testload");
+        FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "testload");
     // Write directly to the file to keep old entries for testing.
     storage::EncryptedStringStorage file_storage(filename);
     ASSERT_TRUE(file_storage.Save(history.SerializeAsString()));
@@ -2256,7 +2256,7 @@ TEST_F(UserHistoryPredictorTest, UserHistoryStorageContainingOldEntries) {
   // Test Save().
   {
     const std::string filename =
-        FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "testsave");
+        FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "testsave");
     UserHistoryStorage storage(filename);
     storage.GetProto() = history;
     ASSERT_TRUE(storage.Save());
diff --git protocol/commands.proto protocol/commands.proto
index 403fdfa01..87f5ab5ad 100644
--- protocol/commands.proto
+++ protocol/commands.proto
@@ -310,7 +310,7 @@ message GenericStorageEntry {
   // Such byte stream cannot be treaed by Java's String class, which
   // is used for PB's string type.
   // Instead, PB's bytes type is converted into ByteString in Java,
-  // which can treat C laguage style string described above.
+  // which can treat C language style string described above.
   repeated bytes value = 3;
 }
 
@@ -361,7 +361,7 @@ message SessionCommand {
     // submitting segments from first one to focused one (inclusive).
     //
     // If no focused candidate (Suggestion, including ZeroQuery suggestion),
-    // first (and only) segment's candiadte of which id is equal to id field of
+    // first (and only) segment's candidate of which id is equal to id field of
     // Input message is submitted.
     // This behavior should be fixed because current cursor position affects
     // nothing. In future, the characters after the cursor should be kept
@@ -683,7 +683,7 @@ message Request {
     // input, the previous composition will be committed.  For
     // example, "ab<space>dc" results "ab " as a committed string and
     // "dc" as a composition.
-    SPACE_OR_CONVERT_COMMITING_COMPOSITION = 1;
+    SPACE_OR_CONVERT_COMMITTING_COMPOSITION = 1;
 
     // Commit the composition and a space.
     COMMIT = 2;
@@ -779,7 +779,7 @@ message Request {
     // cursor key, we'd like to commit the abcde and move the caret to right.
     // So the user will get:
     //   XXXXabcdeY|YYYY
-    // Here, what we need is commiting the "abcde" with the appropriate
+    // Here, what we need is committing the "abcde" with the appropriate
     // caret position. (Note that we need to handle the left cursor key, too).
     // Also, we should *NOT* consume the key, so that the key event will be
     // handled appropriately by the target application.
diff --git protocol/config.proto protocol/config.proto
index 56fd2f23b..8deb5a803 100644
--- protocol/config.proto
+++ protocol/config.proto
@@ -212,7 +212,7 @@ message Config {
   // auto IME turn off feature
   optional bool use_auto_ime_turn_off = 56 [default = true];
 
-  // Toggle to use cascanding window for debuging.
+  // Toggle to use cascanding window for debugging.
   optional bool use_cascading_window = 58 [default = true];
 
   // Shift key mode switch
diff --git protocol/engine_builder.proto protocol/engine_builder.proto
index 90b5f3bb3..1b73b0bb4 100644
--- protocol/engine_builder.proto
+++ protocol/engine_builder.proto
@@ -72,7 +72,7 @@ message EngineReloadResponse {
 
     // The following are errors.
 
-    // Failed to start reload becuase another reload job is currently running.
+    // Failed to start reload because another reload job is currently running.
     ALREADY_RUNNING = 3;
 
     // Erros in data file.
diff --git protocol/renderer_command.proto protocol/renderer_command.proto
index 80ef98c03..27da46cd8 100644
--- protocol/renderer_command.proto
+++ protocol/renderer_command.proto
@@ -155,7 +155,7 @@ message RendererCommand {
     // HWND of the window where composition is displayed.
     optional uint32 target_window_handle = 4;
     // used in Windows:
-    // Preffered font for composition string.
+    // Preferred font for composition string.
     optional WinLogFont composition_font = 5;
 
     // Represents IM Framework used in the client.
@@ -185,7 +185,7 @@ message RendererCommand {
 
     // used in Windows:
     // Indicates if a UI element is expected to be displayed or not.  Note
-    // taht |RendererCommand::visible| should be prior to these flags, that is,
+    // that |RendererCommand::visible| should be prior to these flags, that is,
     // you should hide all UI elements if |RendererCommand::visible| is false
     // regardless of the visibility specified in this field.
     enum UIVisibility {
diff --git protocol/user_dictionary_storage.proto protocol/user_dictionary_storage.proto
index 4fdc7019e..ee47cd554 100644
--- protocol/user_dictionary_storage.proto
+++ protocol/user_dictionary_storage.proto
@@ -92,7 +92,7 @@ message UserDictionary {
 
   // set false if this dictionary is not used.
   // Even if |enabled| is false, the dictionary
-  // it self is visible to user.
+  // itself is visible to user.
   optional bool enabled = 2 [default = true];
 
   // name of dictionary
@@ -284,7 +284,7 @@ message UserDictionaryCommandStatus {
     FILE_NOT_FOUND = 6;
     INVALID_FILE_FORMAT = 7;
 
-    // Note: currently if we recieve this error status,
+    // Note: currently if we receive this error status,
     // the file is actually saved.
     FILE_SIZE_LIMIT_EXCEEDED = 8;
     DICTIONARY_SIZE_LIMIT_EXCEEDED = 9;
diff --git renderer/BUILD renderer/BUILD
index 0d905fcbf..bf71b05eb 100644
--- renderer/BUILD
+++ renderer/BUILD
@@ -33,6 +33,8 @@ load(
     "cc_binary_mozc",
     "cc_library_mozc",
     "cc_test_mozc",
+    "info_plist_mozc",
+    "macos_application_mozc",
     "objc_library_mozc",
     "select_mozc",
 )
@@ -40,9 +42,7 @@ load(
     "//:config.bzl",
     "BRANDING",
     "MACOS_BUNDLE_ID_PREFIX",
-    "MACOS_MIN_OS_VER",
 )
-load("@build_bazel_rules_apple//apple:macos.bzl", "macos_application")
 
 package(default_visibility = ["//:__subpackages__"])
 
@@ -101,7 +101,6 @@ cc_library_mozc(
     deps = [
         ":renderer_interface",
         "//base",
-        "//base:flags",
         "//base:logging",
         "//base:port",
         "//base:system_util",
@@ -113,6 +112,7 @@ cc_library_mozc(
         "//ipc:process_watch_dog",
         "//protocol:config_proto",
         "//protocol:renderer_proto",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
@@ -128,7 +128,6 @@ cc_test_mozc(
         ":renderer_interface",
         ":renderer_server",
         "//base",
-        "//base:flags",
         "//base:logging",
         "//base:port",
         "//base:system_util",
@@ -136,6 +135,7 @@ cc_test_mozc(
         "//ipc:ipc_test_util",
         "//protocol:renderer_proto",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -310,7 +310,7 @@ cc_binary_mozc(
     deps = [
         ":mozc_renderer_lib",
         "//base:crash_report_handler",
-        "//base:flags",
+        "@com_google_absl//absl/flags:flag",
         "//base:init_mozc",
         "//base:run_level",
         "//base:system_util",
@@ -364,13 +364,12 @@ cc_test_mozc(
 )
 
 # macOS
-macos_application(
+macos_application_mozc(
     name = "mozc_renderer_macos",
     app_icons = ["//data/images/mac:product_icon.icns"],
     bundle_id = MACOS_BUNDLE_ID_PREFIX + ".Renderer",
     bundle_name = BRANDING + "Renderer",
-    infoplists = [":gen_mozc_renderer_info_plist"],
-    minimum_os_version = MACOS_MIN_OS_VER,
+    infoplists = [":mozc_renderer_info_plist"],
     resources = ["//data/images/mac:candidate_window_logo.tiff"],
     deps = [":mozc_renderer_main_macos"],
     # When we support Breakpad, uncomment the following block.
@@ -385,12 +384,12 @@ cc_library_mozc(
     deps = [
         ":mozc_renderer_lib_macos",
         "//base:crash_report_handler",
-        "//base:flags",
         "//base:init_mozc",
         "//base:run_level",
         "//base:system_util",
         "//base:util",
         "//config:stats_config_util",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -448,17 +447,8 @@ objc_library_mozc(
     ]),
 )
 
-genrule(
-    name = "gen_mozc_renderer_info_plist",
-    srcs = [
-        "mac/Info.plist",
-        "//base:mozc_version_txt",
-    ],
+info_plist_mozc(
+    name = "mozc_renderer_info_plist",
+    srcs = ["mac/Info.plist"],
     outs = ["Info.plist"],
-    cmd = ("$(location //build_tools:tweak_info_plist)" +
-           " --output $@" +
-           " --input $(location mac/Info.plist)" +
-           " --version_file $(location //base:mozc_version_txt)" +
-           " --branding " + BRANDING),
-    exec_tools = ["//build_tools:tweak_info_plist"],
 )
diff --git renderer/mac/CandidateController.mm renderer/mac/CandidateController.mm
index 587f432e1..f6c6ee741 100644
--- renderer/mac/CandidateController.mm
+++ renderer/mac/CandidateController.mm
@@ -239,7 +239,7 @@ int GetBaseScreenHeight() {
   const mozc::Rect display_rect = GetNearestDisplayRect(preedit_rect);
 
   // Align candidate window.
-  // Initialize the the position.  We use (left, bottom) of preedit as
+  // Initialize the position.  We use (left, bottom) of preedit as
   // the top-left position of the window because we want to show the
   // window just below of the preedit.
   const TableLayout *candidate_layout = candidate_window_->GetTableLayout();
diff --git renderer/mozc_renderer.rc renderer/mozc_renderer.rc
index bf07eb278..962b84b80 100644
Binary files renderer/mozc_renderer.rc and renderer/mozc_renderer.rc differ
diff --git renderer/mozc_renderer_main.cc renderer/mozc_renderer_main.cc
index 61fa81d7c..4aa5c9bf2 100644
--- renderer/mozc_renderer_main.cc
+++ renderer/mozc_renderer_main.cc
@@ -34,12 +34,13 @@
 #endif  // OS_WIN, ENABLE_GTK_RENDERER
 
 #include "base/crash_report_handler.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/run_level.h"
 #include "base/system_util.h"
 #include "base/util.h"
 #include "config/stats_config_util.h"
+#include "absl/flags/declare.h"
+#include "absl/flags/flag.h"
 
 #ifdef OS_WIN
 #include "base/win_util.h"
@@ -64,7 +65,7 @@
 #include "renderer/unix/window_manager.h"
 #endif  // OS_WIN, __APPLE__, ENABLE_GTK_RENDERER
 
-MOZC_DECLARE_FLAG(bool, restricted);
+ABSL_DECLARE_FLAG(bool, restricted);
 
 int main(int argc, char *argv[]) {
   const mozc::RunLevel::RunLevelType run_level =
@@ -91,7 +92,7 @@ int main(int argc, char *argv[]) {
 
   // restricted mode
   if (run_level == mozc::RunLevel::RESTRICTED) {
-    mozc::SetFlag(&FLAGS_restricted, true);
+    absl::SetFlag(&FLAGS_restricted, true);
   }
 
   if (mozc::config::StatsConfigUtil::IsEnabled()) {
diff --git renderer/renderer_client.h renderer/renderer_client.h
index 25ca55ef2..4a063c1e0 100644
--- renderer/renderer_client.h
+++ renderer/renderer_client.h
@@ -57,7 +57,7 @@ class RendererLauncherInterface {
   // do not use this method unless protocol version mismatch
   virtual bool ForceTerminateRenderer(const std::string &name) = 0;
 
-  // called when fatal error occured
+  // called when fatal error occurred
   virtual void OnFatal(RendererErrorType type) = 0;
 
   // return true if the renderer is running
diff --git renderer/renderer_server.cc renderer/renderer_server.cc
index fcbed2d54..b57dec26d 100644
--- renderer/renderer_server.cc
+++ renderer/renderer_server.cc
@@ -37,7 +37,6 @@
 
 #include "base/compiler_specific.h"
 #include "base/const.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/port.h"
 #include "base/system_util.h"
@@ -49,12 +48,13 @@
 #include "protocol/config.pb.h"
 #include "protocol/renderer_command.pb.h"
 #include "renderer/renderer_interface.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 // By default, mozc_renderer quits when user-input continues to be
 // idle for 10min.
-MOZC_FLAG(int32, timeout, 10 * 60, "timeout of candidate server (sec)");
-MOZC_FLAG(bool, restricted, false,
+ABSL_FLAG(int32, timeout, 10 * 60, "timeout of candidate server (sec)");
+ABSL_FLAG(bool, restricted, false,
           "launch candidates server with restricted mode");
 
 namespace mozc {
@@ -174,14 +174,14 @@ RendererServer::RendererServer()
       send_command_(new RendererServerSendCommand) {
   watch_dog_ = absl::make_unique<ParentApplicationWatchDog>(this);
   watch_dog_->StartWatchDog();
-  if (mozc::GetFlag(FLAGS_restricted)) {
-    mozc::SetFlag(&FLAGS_timeout,
+  if (absl::GetFlag(FLAGS_restricted)) {
+    absl::SetFlag(&FLAGS_timeout,
                   // set 60sec with restricted mode
-                  std::min(mozc::GetFlag(FLAGS_timeout), 60));
+                  std::min(absl::GetFlag(FLAGS_timeout), 60));
   }
 
   timeout_ = 1000 * std::max(3, std::min(24 * 60 * 60,
-                                         mozc::GetFlag(FLAGS_timeout)));
+                                         absl::GetFlag(FLAGS_timeout)));
   VLOG(2) << "timeout is set to be : " << timeout_;
 
 #ifndef MOZC_NO_LOGGING
diff --git renderer/renderer_server_test.cc renderer/renderer_server_test.cc
index e0540cdcb..8f209a611 100644
--- renderer/renderer_server_test.cc
+++ renderer/renderer_server_test.cc
@@ -32,7 +32,6 @@
 #include <memory>
 #include <string>
 
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/port.h"
 #include "base/system_util.h"
@@ -43,6 +42,7 @@
 #include "renderer/renderer_interface.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace renderer {
@@ -121,12 +121,12 @@ class DummyRendererLauncher : public RendererLauncherInterface {
 class RendererServerTest : public ::testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   }
 };
 
 TEST_F(RendererServerTest, IPCTest) {
-  SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+  SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   mozc::IPCClientFactoryOnMemory on_memory_client_factory;
 
   std::unique_ptr<TestRendererServer> server(new TestRendererServer);
diff --git renderer/unix/candidate_window_test.cc renderer/unix/candidate_window_test.cc
index 3bedcf1f7..506ec1188 100644
--- renderer/unix/candidate_window_test.cc
+++ renderer/unix/candidate_window_test.cc
@@ -60,7 +60,7 @@ namespace renderer {
 namespace gtk {
 
 namespace {
-// Following variable is used testing and it is contant but due to API
+// Following variable is used testing and it is constant but due to API
 // restriction, can not modify const modifier.
 GtkWidget *kDummyWindow = reinterpret_cast<GtkWidget *>(0x12345678);
 GtkWidget *kDummyCanvas = reinterpret_cast<GtkWidget *>(0x87654321);
@@ -1395,7 +1395,7 @@ TEST_F(CandidateWindowTest, OnMouseLeftUpTest) {
     FinalizeTestKit(&testkit);
   }
   {
-    SCOPED_TRACE("Exepcted ID will be set by candidate index.");
+    SCOPED_TRACE("Expected ID will be set by candidate index.");
     const size_t kTestRound = 10;
     for (size_t i = 0; i < kTestRound; ++i) {
       SendCommandInterfaceMock interface_mock;
diff --git renderer/unix/draw_tool_interface.h renderer/unix/draw_tool_interface.h
index 266d53eee..b9d22d7df 100644
--- renderer/unix/draw_tool_interface.h
+++ renderer/unix/draw_tool_interface.h
@@ -58,7 +58,7 @@ class DrawToolInterface {
   virtual void Save() = 0;
   virtual void Restore() = 0;
 
-  // Draws rectangle and fill inside of it with spcified color.
+  // Draws rectangle and fill inside of it with specified color.
   virtual void FillRect(const Rect &rect, const RGBA &color) = 0;
 
   // Draws rectangle with specified color.
diff --git renderer/unix/gtk_window_base_test.cc renderer/unix/gtk_window_base_test.cc
index 35f066367..67b9897ca 100644
--- renderer/unix/gtk_window_base_test.cc
+++ renderer/unix/gtk_window_base_test.cc
@@ -44,7 +44,7 @@ namespace renderer {
 namespace gtk {
 
 namespace {
-// Following variable is used testing and it is contant but due to API
+// Following variable is used testing and it is constant but due to API
 // restriction, can not modify const modifier.
 GtkWidget *kDummyWindow = reinterpret_cast<GtkWidget *>(0x12345678);
 GtkWidget *kDummyCanvas = reinterpret_cast<GtkWidget *>(0x87654321);
diff --git renderer/unix/infolist_window.h renderer/unix/infolist_window.h
index fe182534a..e717ac1f9 100644
--- renderer/unix/infolist_window.h
+++ renderer/unix/infolist_window.h
@@ -78,13 +78,13 @@ class InfolistWindow : public GtkWindowBase {
 
   void Draw();
 
-  // Draws specified description row and returns it's height.
+  // Draws specified description row and returns its height.
   int DrawRow(int row, int ypos);
 
   // Gets target rendering rects.
   RenderingRowRects GetRowRects(int row, int ypos);
 
-  // Draws caption string and returns it's height.
+  // Draws caption string and returns its height.
   int DrawCaption();
 
   // Draws infolist window frame line.
diff --git renderer/unix/infolist_window_test.cc renderer/unix/infolist_window_test.cc
index 540ce2943..98be2cb23 100644
--- renderer/unix/infolist_window_test.cc
+++ renderer/unix/infolist_window_test.cc
@@ -49,7 +49,7 @@ namespace renderer {
 namespace gtk {
 
 namespace {
-// Following variable is used testing and it is contant but due to API
+// Following variable is used testing and it is constant but due to API
 // restriction, can not modify const modifier.
 GtkWidget *kDummyWindow = reinterpret_cast<GtkWidget *>(0x12345678);
 GtkWidget *kDummyCanvas = reinterpret_cast<GtkWidget *>(0x87654321);
diff --git renderer/unix/unix_renderer_test.cc renderer/unix/unix_renderer_test.cc
index fc9f954ae..0c1c98fed 100644
--- renderer/unix/unix_renderer_test.cc
+++ renderer/unix/unix_renderer_test.cc
@@ -69,7 +69,7 @@ TEST(UnixRendererTest, ExecCommand) {
     EXPECT_FALSE(renderer.ExecCommand(command));
   }
   {
-    SCOPED_TRACE("UPDATE with visibile = true update layout");
+    SCOPED_TRACE("UPDATE with visible = true update layout");
 
     WindowManagerMock *wm_mock = new WindowManagerMock();
     commands::RendererCommand command;
@@ -83,7 +83,7 @@ TEST(UnixRendererTest, ExecCommand) {
     EXPECT_TRUE(renderer.ExecCommand(command));
   }
   {
-    SCOPED_TRACE("UPDATE with visibile = false call HideAllWindows");
+    SCOPED_TRACE("UPDATE with visible = false call HideAllWindows");
 
     WindowManagerMock *wm_mock = new WindowManagerMock();
     commands::RendererCommand command;
diff --git renderer/unix/unix_server.h renderer/unix/unix_server.h
index e152f38da..7a100320f 100644
--- renderer/unix/unix_server.h
+++ renderer/unix/unix_server.h
@@ -67,9 +67,9 @@ class UnixServer : public RendererServer {
   Mutex mutex_;
   std::unique_ptr<GtkWrapperInterface> gtk_;
 
-  // Following pipe is used to communicate IPC recieving thread and
+  // Following pipe is used to communicate IPC receiving thread and
   // rendering(gtk-main) thread. The gtk-main loop polls following pipe and IPC
-  // recieving thread writes small data to notify gtk-main thread to update when
+  // receiving thread writes small data to notify gtk-main thread to update when
   // new packet is arrived.
   int pipefd_[2];
 
diff --git renderer/unix/unix_server_test.cc renderer/unix/unix_server_test.cc
index 1324a97e2..d11cc3963 100644
--- renderer/unix/unix_server_test.cc
+++ renderer/unix/unix_server_test.cc
@@ -29,11 +29,11 @@
 
 #include "renderer/unix/unix_server.h"
 
-#include "base/flags.h"
 #include "base/system_util.h"
 #include "renderer/unix/gtk_wrapper_mock.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 using testing::_;
 using testing::Return;
@@ -46,7 +46,7 @@ namespace gtk {
 class UnixServerTest : public testing::Test {
  protected:
   virtual void SetUp() {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   }
 };
 
diff --git renderer/win32/gen_pbgra32_bitmap.cc renderer/win32/gen_pbgra32_bitmap.cc
index fa3376794..58fbf4f6c 100644
--- renderer/win32/gen_pbgra32_bitmap.cc
+++ renderer/win32/gen_pbgra32_bitmap.cc
@@ -34,14 +34,14 @@
 #include <memory>
 
 #include "base/file_stream.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/port.h"
 #include "base/util.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, src, "", "path to the input PNG file");
-MOZC_FLAG(string, dest, "", "path to the output BMP file");
+ABSL_FLAG(std::string, src, "", "path to the input PNG file");
+ABSL_FLAG(std::string, dest, "", "path to the output BMP file");
 
 using ::std::max;
 using ::std::min;
@@ -61,7 +61,7 @@ const uint32 kMaxBitmapHeight = 16384;
 
 bool ConvertMain() {
   std::wstring wide_src;
-  mozc::Util::UTF8ToWide(mozc::GetFlag(FLAGS_src), &wide_src);
+  mozc::Util::UTF8ToWide(absl::GetFlag(FLAGS_src), &wide_src);
   std::unique_ptr<Gdiplus::Bitmap> image(
       Gdiplus::Bitmap::FromFile(wide_src.c_str()));
 
@@ -119,7 +119,7 @@ bool ConvertMain() {
   header.pixel_data_size = pixel_data_bytes;
 
   mozc::OutputFileStream output_file(
-      mozc::GetFlag(FLAGS_dest).c_str(),
+      absl::GetFlag(FLAGS_dest).c_str(),
       std::ios::out | std::ios::binary | std::ios::trunc);
   if (!output_file.good()) {
     return false;
@@ -145,11 +145,11 @@ bool ConvertMain() {
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
-  if (mozc::GetFlag(FLAGS_src).empty()) {
+  if (absl::GetFlag(FLAGS_src).empty()) {
     std::cout << "Specify --src option";
     return kErrorLevelFail;
   }
-  if (mozc::GetFlag(FLAGS_dest).empty()) {
+  if (absl::GetFlag(FLAGS_dest).empty()) {
     std::cout << "Specify --dest option";
     return kErrorLevelFail;
   }
diff --git renderer/win32/win32_renderer_client.cc renderer/win32/win32_renderer_client.cc
index 400865117..bcfe7f9fb 100644
--- renderer/win32/win32_renderer_client.cc
+++ renderer/win32/win32_renderer_client.cc
@@ -55,7 +55,7 @@ Mutex *g_mutex = nullptr;
 // Represents the module handle of this module.
 volatile HMODULE g_module = nullptr;
 
-// True if the the DLL received DLL_PROCESS_DETACH notification.
+// True if the DLL received DLL_PROCESS_DETACH notification.
 volatile bool g_module_unloaded = false;
 
 // Represents the number of UI threads that are recognized by this module.
diff --git rewriter/BUILD rewriter/BUILD
index 84ca5e340..ae183e7d5 100644
--- rewriter/BUILD
+++ rewriter/BUILD
@@ -60,7 +60,6 @@ cc_test_mozc(
     deps = [
         ":merger_rewriter",
         "//base",
-        "//base:flags",
         "//base:stl_util",
         "//base:system_util",
         "//config:config_handler",
@@ -69,6 +68,7 @@ cc_test_mozc(
         "//protocol:config_proto",
         "//request:conversion_request",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
@@ -83,7 +83,6 @@ cc_library_mozc(
         ":collocation_util",
         ":rewriter_interface",
         "//base",
-        "//base:flags",
         "//base:hash",
         "//base:logging",
         "//base:port",
@@ -94,6 +93,7 @@ cc_library_mozc(
         "//protocol:commands_proto",
         "//request:conversion_request",
         "//storage:existence_filter",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
         "@com_google_absl//absl/strings",
     ],
@@ -107,7 +107,6 @@ cc_test_mozc(
     deps = [
         ":collocation_rewriter",
         "//base",
-        "//base:flags",
         "//base:logging",
         "//base:system_util",
         "//config:config_handler",
@@ -115,6 +114,7 @@ cc_test_mozc(
         "//dictionary:pos_matcher_lib",
         "//request:conversion_request",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
@@ -162,7 +162,6 @@ cc_test_mozc(
         "//base:clock",
         "//base:clock_mock",
         "//base:file_util",
-        "//base:flags",
         "//base:logging",
         "//base:number_util",
         "//base:system_util",
@@ -177,6 +176,7 @@ cc_test_mozc(
         "//protocol:config_proto",
         "//request:conversion_request",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
@@ -190,7 +190,6 @@ cc_library_mozc(
         "//base",
         "//base:config_file_stream",
         "//base:file_util",
-        "//base:flags",
         "//base:logging",
         "//base:port",
         "//base:util",
@@ -202,6 +201,7 @@ cc_library_mozc(
         "//request:conversion_request",
         "//storage:lru_storage",
         "//usage_stats",
+        "@com_google_absl//absl/flags:flag",
     ],
     alwayslink = 1,
 )
@@ -215,7 +215,6 @@ cc_test_mozc(
         ":user_boundary_history_rewriter",
         "//base",
         "//base:file_util",
-        "//base:flags",
         "//base:system_util",
         "//config:config_handler",
         "//converter:converter_mock",
@@ -223,6 +222,7 @@ cc_test_mozc(
         "//protocol:config_proto",
         "//request:conversion_request",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -467,7 +467,6 @@ cc_test_mozc(
     requires_full_emulation = False,
     deps = [
         ":version_rewriter",
-        "//base:flags",
         "//base:system_util",
         "//base:util",
         "//config:config_handler",
@@ -475,6 +474,7 @@ cc_test_mozc(
         "//protocol:commands_proto",
         "//request:conversion_request",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
@@ -514,7 +514,6 @@ cc_test_mozc(
     deps = [
         ":symbol_rewriter",
         "//base",
-        "//base:flags",
         "//base:logging",
         "//base:system_util",
         "//base:util",
@@ -527,6 +526,7 @@ cc_test_mozc(
         "//request:conversion_request",
         "//session:request_test_util",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
         "@com_google_absl//absl/strings",
     ],
@@ -647,12 +647,12 @@ cc_test_mozc(
     deps = [
         ":english_variants_rewriter",
         "//base",
-        "//base:flags",
         "//base:system_util",
         "//converter:segments",
         "//protocol:commands_proto",
         "//request:conversion_request",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
@@ -683,12 +683,12 @@ cc_test_mozc(
     deps = [
         ":fortune_rewriter",
         "//base",
-        "//base:flags",
         "//base:logging",
         "//base:system_util",
         "//converter:segments",
         "//request:conversion_request",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
@@ -717,11 +717,11 @@ cc_test_mozc(
     deps = [
         ":dice_rewriter",
         "//base",
-        "//base:flags",
         "//base:system_util",
         "//converter:segments",
         "//request:conversion_request",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
@@ -755,7 +755,6 @@ cc_test_mozc(
     deps = [
         ":calculator_rewriter",
         "//base",
-        "//base:flags",
         "//base:logging",
         "//base:system_util",
         "//config:config_handler",
@@ -770,6 +769,7 @@ cc_test_mozc(
         "//rewriter/calculator",
         "//rewriter/calculator:calculator_mock",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
@@ -802,7 +802,6 @@ cc_test_mozc(
     deps = [
         ":unicode_rewriter",
         "//base",
-        "//base:flags",
         "//base:port",
         "//base:system_util",
         "//base:util",
@@ -815,6 +814,7 @@ cc_test_mozc(
         "//protocol:config_proto",
         "//request:conversion_request",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
@@ -844,13 +844,13 @@ cc_test_mozc(
     deps = [
         ":user_dictionary_rewriter",
         "//base",
-        "//base:flags",
         "//base:logging",
         "//base:system_util",
         "//base:util",
         "//converter:segments",
         "//request:conversion_request",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
@@ -894,12 +894,12 @@ cc_binary_mozc(
         "//base",
         "//base:file_stream",
         "//base:file_util",
-        "//base:flags",
         "//base:init_mozc_buildtool",
         "//base:logging",
         "//base:util",
         "//data_manager",
         "//data_manager:serialized_dictionary",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -909,12 +909,12 @@ cc_binary_mozc(
     deps = [
         ":rewriter_interface",
         "//base:file_stream",
-        "//base:flags",
         "//base:init_mozc_buildtool",
         "//base:logging",
         "//base:mozc_hash_map",
         "//base:util",
         "//data_manager:serialized_dictionary",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
@@ -1042,10 +1042,10 @@ cc_binary_mozc(
     name = "gen_single_kanji_noun_prefix_data",
     srcs = ["gen_single_kanji_noun_prefix_data.cc"],
     deps = [
-        "//base:flags",
         "//base:init_mozc_buildtool",
         "//base:port",
         "//data_manager:serialized_dictionary",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -1056,7 +1056,6 @@ cc_test_mozc(
     requires_full_emulation = False,
     deps = [
         ":single_kanji_rewriter",
-        "//base:flags",
         "//base:system_util",
         "//base:util",
         "//config:config_handler",
@@ -1067,6 +1066,7 @@ cc_test_mozc(
         "//request:conversion_request",
         "//session:request_test_util",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
@@ -1122,7 +1122,6 @@ cc_test_mozc(
     deps = [
         ":focus_candidate_rewriter",
         "//base",
-        "//base:flags",
         "//base:number_util",
         "//base:system_util",
         "//config:config_handler",
@@ -1130,6 +1129,7 @@ cc_test_mozc(
         "//data_manager/testing:mock_data_manager",
         "//testing:gunit_main",
         "//transliteration",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
         "@com_google_absl//absl/strings",
     ],
@@ -1243,7 +1243,6 @@ cc_test_mozc(
     deps = [
         ":command_rewriter",
         "//base",
-        "//base:flags",
         "//base:system_util",
         "//config:config_handler",
         "//converter:segments",
@@ -1251,6 +1250,7 @@ cc_test_mozc(
         "//protocol:config_proto",
         "//request:conversion_request",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -1278,11 +1278,11 @@ cc_test_mozc(
     deps = [
         ":normalization_rewriter",
         "//base",
-        "//base:flags",
         "//base:system_util",
         "//converter:segments",
         "//request:conversion_request",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
@@ -1322,11 +1322,11 @@ cc_binary_mozc(
     deps = [
         "//base",
         "//base:file_stream",
-        "//base:flags",
         "//base:init_mozc_buildtool",
         "//base:logging",
         "//base:serialized_string_array",
         "//base:util",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
@@ -1367,7 +1367,6 @@ cc_test_mozc(
         ":rewriter_interface",
         ":usage_rewriter",
         "//base",
-        "//base:flags",
         "//base:system_util",
         "//config:config_handler",
         "//converter:segments",
@@ -1381,6 +1380,7 @@ cc_test_mozc(
         "//protocol:config_proto",
         "//request:conversion_request",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
         "@com_google_absl//absl/strings",
     ],
@@ -1484,7 +1484,6 @@ cc_library_mozc(
         ":version_rewriter",
         ":zipcode_rewriter",
         "//base",
-        "//base:flags",
         "//base:logging",
         "//base:port",
         "//converter:converter_interface",
@@ -1492,6 +1491,7 @@ cc_library_mozc(
         "//dictionary:dictionary_interface",
         "//dictionary:pos_group",
         "//dictionary:pos_matcher_lib",
+        "@com_google_absl//absl/flags:flag",
     ],
     alwayslink = 1,
 )
@@ -1532,7 +1532,6 @@ cc_test_mozc(
         "rewriter",
         ":rewriter_interface",
         "//base",
-        "//base:flags",
         "//base:system_util",
         "//config:config_handler",
         "//converter:converter_mock",
@@ -1541,6 +1540,7 @@ cc_test_mozc(
         "//dictionary:pos_group",
         "//request:conversion_request",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
@@ -1588,9 +1588,9 @@ cc_binary_mozc(
     deps = [
         ":gen_existence_data",
         "//base:file_stream",
-        "//base:flags",
         "//base:init_mozc_buildtool",
         "//base:logging",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -1600,10 +1600,10 @@ cc_binary_mozc(
     deps = [
         ":gen_existence_data",
         "//base:file_stream",
-        "//base:flags",
         "//base:init_mozc_buildtool",
         "//base:logging",
         "//base:util",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
diff --git rewriter/calculator/calculator_test.cc rewriter/calculator/calculator_test.cc
index 299107812..16c50311b 100644
--- rewriter/calculator/calculator_test.cc
+++ rewriter/calculator/calculator_test.cc
@@ -85,7 +85,7 @@ TEST(CalculatorTest, BasicTest) {
   // These are not expressions
   // apparently
   VerifyRejection(calculator, "test");
-  // Expressoin must be ended with equal '='.
+  // Expression must be ended with equal '='.
   VerifyRejection(calculator, "5+4");
   // Expression must include at least one operator other than parentheses.
   VerifyRejection(calculator, "111=");
diff --git rewriter/calculator_rewriter_test.cc rewriter/calculator_rewriter_test.cc
index f34401cf7..01daa68ca 100644
--- rewriter/calculator_rewriter_test.cc
+++ rewriter/calculator_rewriter_test.cc
@@ -32,7 +32,6 @@
 #include <memory>
 #include <string>
 
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/system_util.h"
 #include "config/config_handler.h"
@@ -48,6 +47,7 @@
 #include "rewriter/calculator/calculator_mock.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 namespace mozc {
@@ -116,7 +116,7 @@ class CalculatorRewriterTest : public ::testing::Test {
   }
 
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
 
     // use mock
     CalculatorFactory::SetCalculator(&calculator_mock_);
diff --git rewriter/collocation_rewriter.cc rewriter/collocation_rewriter.cc
index 913fac238..ecc3943c9 100644
--- rewriter/collocation_rewriter.cc
+++ rewriter/collocation_rewriter.cc
@@ -34,7 +34,6 @@
 #include <string>
 #include <vector>
 
-#include "base/flags.h"
 #include "base/hash.h"
 #include "base/logging.h"
 #include "base/util.h"
@@ -44,11 +43,12 @@
 #include "request/conversion_request.h"
 #include "rewriter/collocation_util.h"
 #include "storage/existence_filter.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 #include "absl/strings/str_cat.h"
 #include "absl/strings/string_view.h"
 
-MOZC_FLAG(bool, use_collocation, true, "use collocation rewrite");
+ABSL_FLAG(bool, use_collocation, true, "use collocation rewrite");
 
 namespace mozc {
 
@@ -261,7 +261,7 @@ bool IsNaturalContent(const Segment::Candidate &cand,
   const size_t aux_value_len = Util::CharsLen(aux_value);
   const size_t value_len = Util::CharsLen(value);
 
-  // "<XXいる|>" can be rewrited to "<YY|いる>" and vice versa
+  // "<XXいる|>" can be rewrote to "<YY|いる>" and vice versa
   {
     static const char kPat[] = "いる";  // "いる"
     const absl::string_view kSuffix(kPat, arraysize(kPat) - 1);
@@ -286,7 +286,7 @@ bool IsNaturalContent(const Segment::Candidate &cand,
     }
   }
 
-  // "<XXせる|>" can be rewrited to "<YY|せる>" and vice versa
+  // "<XXせる|>" can be rewrote to "<YY|せる>" and vice versa
   {
     const char kPat[] = "せる";
     const absl::string_view kSuffix(kPat, arraysize(kPat) - 1);
@@ -313,7 +313,7 @@ bool IsNaturalContent(const Segment::Candidate &cand,
 
   const Util::ScriptType content_script_type = Util::GetScriptType(content);
 
-  // "<XX|する>" can be rewrited using "<XXす|る>" and "<XX|する>"
+  // "<XX|する>" can be rewrote using "<XXす|る>" and "<XX|する>"
   // in "<XX|する>", XX must be single script type
   {
     static const char kPat[] = "する";
@@ -334,7 +334,7 @@ bool IsNaturalContent(const Segment::Candidate &cand,
     }
   }
 
-  // "<XXる>" can be rewrited using "<XX|る>"
+  // "<XXる>" can be rewrote using "<XX|る>"
   // "まとめる", "衰える"
   {
     static const char kPat[] = "る";
@@ -349,7 +349,7 @@ bool IsNaturalContent(const Segment::Candidate &cand,
     }
   }
 
-  // "<XXす>" can be rewrited using "XXする"
+  // "<XXす>" can be rewrote using "XXする"
   {
     static const char kPat[] = "す";
     const absl::string_view kSuffix(kPat, arraysize(kPat) - 1);
@@ -366,7 +366,7 @@ bool IsNaturalContent(const Segment::Candidate &cand,
     }
   }
 
-  // "<XXし|た>" can be rewrited using "<XX|した>"
+  // "<XXし|た>" can be rewrote using "<XX|した>"
   {
     static const char kPat[] = "した";
     const absl::string_view kShi(kPat, 3), kTa(kPat + 3, 3);
@@ -448,7 +448,7 @@ bool CollocationRewriter::RewriteCollocation(Segments *segments) const {
 
   for (size_t i = segments->history_segments_size();
        i < segments->segments_size(); ++i) {
-    bool rewrited_next = false;
+    bool rewrote_next = false;
 
     if (IsKeyUnknown(segments->segment(i))) {
       continue;
@@ -458,12 +458,12 @@ bool CollocationRewriter::RewriteCollocation(Segments *segments) const {
         RewriteUsingNextSegment(segments->mutable_segment(i + 1),
                                 segments->mutable_segment(i))) {
       changed = true;
-      rewrited_next = true;
+      rewrote_next = true;
       segs_changed[i] = true;
       segs_changed[i + 1] = true;
     }
 
-    if (!segs_changed[i] && !rewrited_next && i > 0 &&
+    if (!segs_changed[i] && !rewrote_next && i > 0 &&
         RewriteFromPrevSegment(segments->segment(i - 1).candidate(0),
                                segments->mutable_segment(i))) {
       changed = true;
@@ -566,7 +566,7 @@ CollocationRewriter::~CollocationRewriter() {}
 
 bool CollocationRewriter::Rewrite(const ConversionRequest &request,
                                   Segments *segments) const {
-  if (!mozc::GetFlag(FLAGS_use_collocation)) {
+  if (!absl::GetFlag(FLAGS_use_collocation)) {
     return false;
   }
   return RewriteCollocation(segments);
diff --git rewriter/collocation_rewriter_test.cc rewriter/collocation_rewriter_test.cc
index 62c08f8b4..14295dc04 100644
--- rewriter/collocation_rewriter_test.cc
+++ rewriter/collocation_rewriter_test.cc
@@ -33,7 +33,6 @@
 #include <memory>
 #include <string>
 
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/system_util.h"
 #include "config/config_handler.h"
@@ -42,6 +41,7 @@
 #include "request/conversion_request.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 namespace mozc {
@@ -80,7 +80,7 @@ class CollocationRewriterTest : public ::testing::Test {
   ~CollocationRewriterTest() override = default;
 
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
 
     const mozc::testing::MockDataManager data_manager;
     pos_matcher_.Set(data_manager.GetPOSMatcherData());
diff --git rewriter/command_rewriter_test.cc rewriter/command_rewriter_test.cc
index e5b2d7e2c..21c3e26f1 100644
--- rewriter/command_rewriter_test.cc
+++ rewriter/command_rewriter_test.cc
@@ -31,7 +31,6 @@
 
 #include <string>
 
-#include "base/flags.h"
 #include "base/system_util.h"
 #include "config/config_handler.h"
 #include "converter/segments.h"
@@ -40,6 +39,7 @@
 #include "request/conversion_request.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace {
@@ -73,7 +73,7 @@ class CommandRewriterTest : public ::testing::Test {
   }
 
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     config::ConfigHandler::GetDefaultConfig(&config_);
     request_.Clear();
   }
diff --git rewriter/date_rewriter_test.cc rewriter/date_rewriter_test.cc
index d1f4a9eda..d40256b19 100644
--- rewriter/date_rewriter_test.cc
+++ rewriter/date_rewriter_test.cc
@@ -269,7 +269,7 @@ TEST_F(DateRewriterTest, DateRewriteTest) {
                                      "4月18日",
                                      "月曜日"};
 
-    // If initial count of candidate is 1, date rewrited candidate start from 1.
+    // If initial count of candidate is 1, date rewrote candidate start from 1.
     // "きょう", "今日"
     InitSegment("きょう", "今日", &segments);
     EXPECT_TRUE(rewriter.Rewrite(request, &segments));
@@ -282,7 +282,7 @@ TEST_F(DateRewriterTest, DateRewriteTest) {
     }
 
     // If initial count of candidate is 5 and target candidate is located at
-    // index 4, date rewrited candidate start from 5.
+    // index 4, date rewrote candidate start from 5.
     // "きょう", "今日"
     InitSegment("きょう", "今日", &segments);
 
@@ -303,7 +303,7 @@ TEST_F(DateRewriterTest, DateRewriteTest) {
     }
 
     // If initial count of candidate is 5 and target candidate is located at
-    // index 0, date rewrited candidate start from kMinimumDateCandidateIdx.
+    // index 0, date rewrote candidate start from kMinimumDateCandidateIdx.
     // "きょう", "今日"
     InitSegment("きょう", "今日", &segments);
 
diff --git rewriter/dice_rewriter_test.cc rewriter/dice_rewriter_test.cc
index c1d15baab..69d2c5638 100644
--- rewriter/dice_rewriter_test.cc
+++ rewriter/dice_rewriter_test.cc
@@ -32,12 +32,12 @@
 #include <cstddef>
 #include <string>
 
-#include "base/flags.h"
 #include "base/system_util.h"
 #include "converter/segments.h"
 #include "request/conversion_request.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace {
@@ -111,7 +111,7 @@ size_t GetDiceNumberIndex(const Segment &segment) {
 class DiceRewriterTest : public ::testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   }
 };
 
diff --git rewriter/emoticon_rewriter.cc rewriter/emoticon_rewriter.cc
index 32524c842..442447afb 100644
--- rewriter/emoticon_rewriter.cc
+++ rewriter/emoticon_rewriter.cc
@@ -75,7 +75,7 @@ void InsertCandidates(SerializedDictionary::const_iterator begin,
                       size_t initial_insert_pos, size_t initial_insert_size,
                       bool is_no_learning, Segment *segment) {
   if (segment->candidates_size() == 0) {
-    LOG(WARNING) << "candiadtes_size is 0";
+    LOG(WARNING) << "candidates_size is 0";
     return;
   }
 
@@ -90,7 +90,7 @@ void InsertCandidates(SerializedDictionary::const_iterator begin,
 
   std::sort(sorted_value.begin(), sorted_value.end(), ValueCostCompare());
 
-  // after sorting the valeus by |cost|, adjacent candidates
+  // after sorting the values by |cost|, adjacent candidates
   // will have the same value. It is almost OK to use std::unique to
   // remove dup entries, it is not a perfect way though.
   sorted_value.erase(
diff --git rewriter/english_variants_rewriter.cc rewriter/english_variants_rewriter.cc
index f701397a2..b5a15cbd9 100644
--- rewriter/english_variants_rewriter.cc
+++ rewriter/english_variants_rewriter.cc
@@ -120,7 +120,7 @@ bool EnglishVariantsRewriter::ExpandEnglishVariantsWithSegment(
     DCHECK(original_candidate);
 
     // http://b/issue?id=5137299
-    // If the entry is comming from user dictionary,
+    // If the entry is coming from user dictionary,
     // expand English variants.
     if (original_candidate->attributes &
             Segment::Candidate::NO_VARIANTS_EXPANSION &&
diff --git rewriter/english_variants_rewriter_test.cc rewriter/english_variants_rewriter_test.cc
index f8cb95778..7f803c6dc 100644
--- rewriter/english_variants_rewriter_test.cc
+++ rewriter/english_variants_rewriter_test.cc
@@ -32,20 +32,20 @@
 #include <cstddef>
 #include <string>
 
-#include "base/flags.h"
 #include "base/system_util.h"
 #include "converter/segments.h"
 #include "protocol/commands.pb.h"
 #include "request/conversion_request.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 
 class EnglishVariantsRewriterTest : public ::testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   }
 
   bool GetRankFromValue(const Segment &segment, const std::string &value,
diff --git rewriter/focus_candidate_rewriter.cc rewriter/focus_candidate_rewriter.cc
index 019df99f0..00266bc0b 100644
--- rewriter/focus_candidate_rewriter.cc
+++ rewriter/focus_candidate_rewriter.cc
@@ -51,7 +51,7 @@ bool IsConnectorSegment(const Segment &segment) {
   return (segment.key() == "と" || segment.key() == "や");
 }
 
-// Finds value from the candidates list and move the canidate to the top.
+// Finds value from the candidates list and move the candidate to the top.
 bool RewriteCandidate(Segment *segment, const std::string &value) {
   for (int i = 0; i < segment->candidates_size(); ++i) {
     if (segment->candidate(i).content_value == value) {
diff --git rewriter/focus_candidate_rewriter.h rewriter/focus_candidate_rewriter.h
index b2c1b874b..e592f269c 100644
--- rewriter/focus_candidate_rewriter.h
+++ rewriter/focus_candidate_rewriter.h
@@ -73,7 +73,7 @@ class FocusCandidateRewriter : public RewriterInterface {
                              absl::string_view ref_suffix) const;
 
   // Parses the value of a candidate into number and counter suffix.
-  // Simultaneously checks the script type of number.  Here, number candiate is
+  // Simultaneously checks the script type of number.  Here, number candidate is
   // defined to be the following pattern:
   //   * [数][助数詞][並立助詞]?  (e.g., 一階, 二回, ３階や, etc.)
   // Returns false if the value of candidate doesn't match the pattern.
diff --git rewriter/focus_candidate_rewriter_test.cc rewriter/focus_candidate_rewriter_test.cc
index df9d47b63..a92d5fcce 100644
--- rewriter/focus_candidate_rewriter_test.cc
+++ rewriter/focus_candidate_rewriter_test.cc
@@ -33,7 +33,6 @@
 #include <string>
 #include <vector>
 
-#include "base/flags.h"
 #include "base/number_util.h"
 #include "base/system_util.h"
 #include "config/config_handler.h"
@@ -42,6 +41,7 @@
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
 #include "transliteration/transliteration.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 namespace mozc {
@@ -67,7 +67,7 @@ void AddCandidateWithContentValue(Segment *segment, const std::string &value,
 class FocusCandidateRewriterTest : public ::testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     rewriter_ = absl::make_unique<FocusCandidateRewriter>(&mock_data_manager_);
   }
 
diff --git rewriter/fortune_rewriter_test.cc rewriter/fortune_rewriter_test.cc
index 48186d906..00231e504 100644
--- rewriter/fortune_rewriter_test.cc
+++ rewriter/fortune_rewriter_test.cc
@@ -32,13 +32,13 @@
 #include <cstddef>
 #include <string>
 
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/system_util.h"
 #include "converter/segments.h"
 #include "request/conversion_request.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace {
@@ -74,7 +74,7 @@ bool HasFortune(const Segments &segments) {
 class FortuneRewriterTest : public ::testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   }
 };
 
diff --git rewriter/gen_collocation_data_main.cc rewriter/gen_collocation_data_main.cc
index bcb99debb..b4fe04a03 100644
--- rewriter/gen_collocation_data_main.cc
+++ rewriter/gen_collocation_data_main.cc
@@ -41,21 +41,21 @@
 #include <vector>
 
 #include "base/file_stream.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "rewriter/gen_existence_data.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, collocation_data, "", "collocation data text");
-MOZC_FLAG(string, output, "", "output file name (default: stdout)");
-MOZC_FLAG(double, error_rate, 0.00001, "error rate");
-MOZC_FLAG(bool, binary_mode, false, "outputs binary file");
+ABSL_FLAG(std::string, collocation_data, "", "collocation data text");
+ABSL_FLAG(std::string, output, "", "output file name (default: stdout)");
+ABSL_FLAG(double, error_rate, 0.00001, "error rate");
+ABSL_FLAG(bool, binary_mode, false, "outputs binary file");
 
 namespace mozc {
 namespace {
 
 void Convert() {
-  InputFileStream ifs(mozc::GetFlag(FLAGS_collocation_data).c_str());
+  InputFileStream ifs(absl::GetFlag(FLAGS_collocation_data).c_str());
   std::string line;
   std::vector<std::string> entries;
   while (!std::getline(ifs, line).fail()) {
@@ -66,21 +66,21 @@ void Convert() {
   }
 
   std::ostream *ofs = &std::cout;
-  if (!mozc::GetFlag(FLAGS_output).empty()) {
-    if (mozc::GetFlag(FLAGS_binary_mode)) {
-      ofs = new OutputFileStream(mozc::GetFlag(FLAGS_output).c_str(),
+  if (!absl::GetFlag(FLAGS_output).empty()) {
+    if (absl::GetFlag(FLAGS_binary_mode)) {
+      ofs = new OutputFileStream(absl::GetFlag(FLAGS_output).c_str(),
                                  std::ios::out | std::ios::binary);
     } else {
-      ofs = new OutputFileStream(mozc::GetFlag(FLAGS_output).c_str());
+      ofs = new OutputFileStream(absl::GetFlag(FLAGS_output).c_str());
     }
   }
 
-  if (mozc::GetFlag(FLAGS_binary_mode)) {
-    OutputExistenceBinary(entries, ofs, mozc::GetFlag(FLAGS_error_rate));
+  if (absl::GetFlag(FLAGS_binary_mode)) {
+    OutputExistenceBinary(entries, ofs, absl::GetFlag(FLAGS_error_rate));
   } else {
     const std::string kNameSpace = "CollocationData";
     OutputExistenceHeader(entries, kNameSpace, ofs,
-                          mozc::GetFlag(FLAGS_error_rate));
+                          absl::GetFlag(FLAGS_error_rate));
   }
 
   if (ofs != &std::cout) {
@@ -93,11 +93,11 @@ void Convert() {
 int main(int argc, char *argv[]) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
-  if (mozc::GetFlag(FLAGS_collocation_data).empty() && argc > 1) {
-    mozc::SetFlag(&FLAGS_collocation_data, argv[1]);
+  if (absl::GetFlag(FLAGS_collocation_data).empty() && argc > 1) {
+    absl::SetFlag(&FLAGS_collocation_data, argv[1]);
   }
 
-  LOG(INFO) << mozc::GetFlag(FLAGS_collocation_data);
+  LOG(INFO) << absl::GetFlag(FLAGS_collocation_data);
 
   mozc::Convert();
 
diff --git rewriter/gen_collocation_suppression_data_main.cc rewriter/gen_collocation_suppression_data_main.cc
index 0d14199d3..3a44da990 100644
--- rewriter/gen_collocation_suppression_data_main.cc
+++ rewriter/gen_collocation_suppression_data_main.cc
@@ -44,16 +44,16 @@
 #include <vector>
 
 #include "base/file_stream.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/util.h"
 #include "rewriter/gen_existence_data.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, suppression_data, "", "suppression data text");
-MOZC_FLAG(string, output, "", "output file name (default: stdout)");
-MOZC_FLAG(double, error_rate, 0.00001, "error rate");
-MOZC_FLAG(bool, binary_mode, false, "outputs binary file");
+ABSL_FLAG(std::string, suppression_data, "", "suppression data text");
+ABSL_FLAG(std::string, output, "", "output file name (default: stdout)");
+ABSL_FLAG(double, error_rate, 0.00001, "error rate");
+ABSL_FLAG(bool, binary_mode, false, "outputs binary file");
 
 namespace mozc {
 namespace {
@@ -62,11 +62,11 @@ void Convert() {
   const char kSeparator[] = "\t";
   std::vector<std::string> entries;
 
-  if (mozc::GetFlag(FLAGS_suppression_data).empty()) {
+  if (absl::GetFlag(FLAGS_suppression_data).empty()) {
     const std::string kDummyStr = "__NO_DATA__";
     entries.push_back(kDummyStr + kSeparator + kDummyStr);
   } else {
-    InputFileStream ifs(mozc::GetFlag(FLAGS_suppression_data).c_str());
+    InputFileStream ifs(absl::GetFlag(FLAGS_suppression_data).c_str());
     std::string line;
 
     while (!std::getline(ifs, line).fail()) {
@@ -81,21 +81,21 @@ void Convert() {
   }
 
   std::ostream *ofs = &std::cout;
-  if (!mozc::GetFlag(FLAGS_output).empty()) {
-    if (mozc::GetFlag(FLAGS_binary_mode)) {
-      ofs = new OutputFileStream(mozc::GetFlag(FLAGS_output).c_str(),
+  if (!absl::GetFlag(FLAGS_output).empty()) {
+    if (absl::GetFlag(FLAGS_binary_mode)) {
+      ofs = new OutputFileStream(absl::GetFlag(FLAGS_output).c_str(),
                                  std::ios::out | std::ios::binary);
     } else {
-      ofs = new OutputFileStream(mozc::GetFlag(FLAGS_output).c_str());
+      ofs = new OutputFileStream(absl::GetFlag(FLAGS_output).c_str());
     }
   }
 
-  if (mozc::GetFlag(FLAGS_binary_mode)) {
-    OutputExistenceBinary(entries, ofs, mozc::GetFlag(FLAGS_error_rate));
+  if (absl::GetFlag(FLAGS_binary_mode)) {
+    OutputExistenceBinary(entries, ofs, absl::GetFlag(FLAGS_error_rate));
   } else {
     const std::string kNameSpace = "CollocationSuppressionData";
     OutputExistenceHeader(entries, kNameSpace, ofs,
-                          mozc::GetFlag(FLAGS_error_rate));
+                          absl::GetFlag(FLAGS_error_rate));
   }
 
   if (ofs != &std::cout) {
@@ -108,7 +108,7 @@ void Convert() {
 int main(int argc, char *argv[]) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
-  LOG(INFO) << mozc::GetFlag(FLAGS_suppression_data);
+  LOG(INFO) << absl::GetFlag(FLAGS_suppression_data);
 
   mozc::Convert();
 
diff --git rewriter/gen_emoticon_rewriter_data.cc rewriter/gen_emoticon_rewriter_data.cc
index ce866d574..a79f5e12f 100644
--- rewriter/gen_emoticon_rewriter_data.cc
+++ rewriter/gen_emoticon_rewriter_data.cc
@@ -33,17 +33,17 @@
 #include <vector>
 
 #include "base/file_stream.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/mozc_hash_map.h"
 #include "base/util.h"
 #include "data_manager/serialized_dictionary.h"
+#include "absl/flags/flag.h"
 #include "absl/strings/string_view.h"
 
-MOZC_FLAG(string, input, "", "Emoticon dictionary file");
-MOZC_FLAG(string, output_token_array, "", "Output token array");
-MOZC_FLAG(string, output_string_array, "", "Output string array");
+ABSL_FLAG(std::string, input, "", "Emoticon dictionary file");
+ABSL_FLAG(std::string, output_token_array, "", "Output token array");
+ABSL_FLAG(std::string, output_string_array, "", "Output string array");
 
 namespace mozc {
 namespace {
@@ -129,9 +129,9 @@ std::map<std::string, TokenList> ReadEmoticonTsv(const std::string &path) {
 
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
-  const auto &input_data = mozc::ReadEmoticonTsv(mozc::GetFlag(FLAGS_input));
+  const auto &input_data = mozc::ReadEmoticonTsv(absl::GetFlag(FLAGS_input));
   mozc::SerializedDictionary::CompileToFiles(
-      input_data, mozc::GetFlag(FLAGS_output_token_array),
-      mozc::GetFlag(FLAGS_output_string_array));
+      input_data, absl::GetFlag(FLAGS_output_token_array),
+      absl::GetFlag(FLAGS_output_string_array));
   return 0;
 }
diff --git rewriter/gen_single_kanji_noun_prefix_data.cc rewriter/gen_single_kanji_noun_prefix_data.cc
index 0ef651e0f..61df3ab9b 100644
--- rewriter/gen_single_kanji_noun_prefix_data.cc
+++ rewriter/gen_single_kanji_noun_prefix_data.cc
@@ -30,14 +30,14 @@
 #include <map>
 #include <string>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/port.h"
 #include "data_manager/serialized_dictionary.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, output_token_array, "",
+ABSL_FLAG(std::string, output_token_array, "",
           "Output token array of noun prefix dictionary");
-MOZC_FLAG(string, output_string_array, "",
+ABSL_FLAG(std::string, output_string_array, "",
           "Output string array of noun prefix dictionary");
 
 namespace {
@@ -99,7 +99,7 @@ int main(int argc, char **argv) {
     tokens[entry.key].emplace_back(std::move(token));
   }
   mozc::SerializedDictionary::CompileToFiles(
-      tokens, mozc::GetFlag(FLAGS_output_token_array),
-      mozc::GetFlag(FLAGS_output_string_array));
+      tokens, absl::GetFlag(FLAGS_output_token_array),
+      absl::GetFlag(FLAGS_output_string_array));
   return 0;
 }
diff --git rewriter/gen_symbol_rewriter_dictionary_main.cc rewriter/gen_symbol_rewriter_dictionary_main.cc
index bdafb0ecc..790d27387 100644
--- rewriter/gen_symbol_rewriter_dictionary_main.cc
+++ rewriter/gen_symbol_rewriter_dictionary_main.cc
@@ -45,20 +45,22 @@
 
 #include "base/file_stream.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/util.h"
 #include "data_manager/data_manager.h"
 #include "data_manager/serialized_dictionary.h"
 #include "rewriter/dictionary_generator.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, sorting_table, "", "sorting table file");
-MOZC_FLAG(string, ordering_rule, "", "sorting order file");
-MOZC_FLAG(string, input, "", "symbol dictionary file");
-MOZC_FLAG(string, user_pos_manager_data, "", "user pos manager data file");
-MOZC_FLAG(string, output_token_array, "", "output token array binary file");
-MOZC_FLAG(string, output_string_array, "", "output string array binary file");
+ABSL_FLAG(std::string, sorting_table, "", "sorting table file");
+ABSL_FLAG(std::string, ordering_rule, "", "sorting order file");
+ABSL_FLAG(std::string, input, "", "symbol dictionary file");
+ABSL_FLAG(std::string, user_pos_manager_data, "", "user pos manager data file");
+ABSL_FLAG(std::string, output_token_array, "",
+          "output token array binary file");
+ABSL_FLAG(std::string, output_string_array, "",
+          "output string array binary file");
 
 namespace mozc {
 namespace {
@@ -202,34 +204,34 @@ void MakeDictionary(const std::string &symbol_dictionary_file,
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
-  if ((mozc::GetFlag(FLAGS_input).empty() ||
-       mozc::GetFlag(FLAGS_sorting_table).empty() ||
-       mozc::GetFlag(FLAGS_ordering_rule).empty()) &&
+  if ((absl::GetFlag(FLAGS_input).empty() ||
+       absl::GetFlag(FLAGS_sorting_table).empty() ||
+       absl::GetFlag(FLAGS_ordering_rule).empty()) &&
       argc > 3) {
-    mozc::SetFlag(&FLAGS_input, argv[1]);
-    mozc::SetFlag(&FLAGS_sorting_table, argv[2]);
-    mozc::SetFlag(&FLAGS_ordering_rule, argv[3]);
+    absl::SetFlag(&FLAGS_input, argv[1]);
+    absl::SetFlag(&FLAGS_sorting_table, argv[2]);
+    absl::SetFlag(&FLAGS_ordering_rule, argv[3]);
   }
 
   const std::string tmp_text_file =
-      mozc::GetFlag(FLAGS_output_token_array) + ".txt";
+      absl::GetFlag(FLAGS_output_token_array) + ".txt";
 
   // User pos manager data for build tools has no magic number.
   const char *kMagciNumber = "";
   mozc::DataManager data_manager;
   const mozc::DataManager::Status status =
       data_manager.InitUserPosManagerDataFromFile(
-          mozc::GetFlag(FLAGS_user_pos_manager_data), kMagciNumber);
+          absl::GetFlag(FLAGS_user_pos_manager_data), kMagciNumber);
   CHECK_EQ(status, mozc::DataManager::Status::OK);
 
   mozc::rewriter::DictionaryGenerator dictionary(data_manager);
-  mozc::MakeDictionary(mozc::GetFlag(FLAGS_input),
-                       mozc::GetFlag(FLAGS_sorting_table),
-                       mozc::GetFlag(FLAGS_ordering_rule), &dictionary);
+  mozc::MakeDictionary(absl::GetFlag(FLAGS_input),
+                       absl::GetFlag(FLAGS_sorting_table),
+                       absl::GetFlag(FLAGS_ordering_rule), &dictionary);
   dictionary.Output(tmp_text_file);
   mozc::SerializedDictionary::CompileToFiles(
-      tmp_text_file, mozc::GetFlag(FLAGS_output_token_array),
-      mozc::GetFlag(FLAGS_output_string_array));
+      tmp_text_file, absl::GetFlag(FLAGS_output_token_array),
+      absl::GetFlag(FLAGS_output_string_array));
   mozc::FileUtil::Unlink(tmp_text_file);
 
   return 0;
diff --git rewriter/gen_usage_rewriter_dictionary_main.cc rewriter/gen_usage_rewriter_dictionary_main.cc
index aaf4c069e..d92504f00 100644
--- rewriter/gen_usage_rewriter_dictionary_main.cc
+++ rewriter/gen_usage_rewriter_dictionary_main.cc
@@ -100,23 +100,24 @@
 #include <vector>
 
 #include "base/file_stream.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/serialized_string_array.h"
 #include "base/util.h"
+#include "absl/flags/flag.h"
 #include "absl/strings/string_view.h"
 
-MOZC_FLAG(string, usage_data_file, "", "usage data file");
-MOZC_FLAG(string, cforms_file, "", "cforms file");
-MOZC_FLAG(string, output_base_conjugation_suffix, "",
+ABSL_FLAG(std::string, usage_data_file, "", "usage data file");
+ABSL_FLAG(std::string, cforms_file, "", "cforms file");
+ABSL_FLAG(std::string, output_base_conjugation_suffix, "",
           "output base conjugation suffix array");
-MOZC_FLAG(string, output_conjugation_suffix, "",
+ABSL_FLAG(std::string, output_conjugation_suffix, "",
           "output conjugation suffix array");
-MOZC_FLAG(string, output_conjugation_index, "",
+ABSL_FLAG(std::string, output_conjugation_index, "",
           "output conjugation index array");
-MOZC_FLAG(string, output_usage_item_array, "", "output array of usage items");
-MOZC_FLAG(string, output_string_array, "", "output string array");
+ABSL_FLAG(std::string, output_usage_item_array, "",
+          "output array of usage items");
+ABSL_FLAG(std::string, output_string_array, "", "output string array");
 
 namespace mozc {
 namespace {
@@ -257,13 +258,13 @@ void Convert() {
   // Load cforms_file
   std::map<std::string, std::vector<ConjugationType>> inflection_map;
   std::map<std::string, ConjugationType> baseform_map;
-  LoadConjugation(mozc::GetFlag(FLAGS_cforms_file), &inflection_map,
+  LoadConjugation(absl::GetFlag(FLAGS_cforms_file), &inflection_map,
                   &baseform_map);
 
   // Load usage_data_file
   std::vector<UsageItem> usage_entries;
   std::vector<std::string> conjugation_list;
-  LoadUsage(mozc::GetFlag(FLAGS_usage_data_file), &usage_entries,
+  LoadUsage(absl::GetFlag(FLAGS_usage_data_file), &usage_entries,
             &conjugation_list);
   RemoveBaseformConjugationSuffix(baseform_map, &usage_entries);
   std::sort(usage_entries.begin(), usage_entries.end(), UsageItemKeynameCmp);
@@ -299,7 +300,7 @@ void Convert() {
   // Output base conjugation suffix data.
   {
     OutputFileStream ostream(
-        mozc::GetFlag(FLAGS_output_base_conjugation_suffix).c_str(),
+        absl::GetFlag(FLAGS_output_base_conjugation_suffix).c_str(),
         std::ios_base::out | std::ios_base::binary);
     for (const auto &conj : conjugation_list) {
       const uint32 key_suffix_index =
@@ -315,7 +316,7 @@ void Convert() {
   std::vector<int> conjugation_index(conjugation_list.size() + 1);
   {
     OutputFileStream ostream(
-        mozc::GetFlag(FLAGS_output_conjugation_suffix).c_str(),
+        absl::GetFlag(FLAGS_output_conjugation_suffix).c_str(),
         std::ios_base::out | std::ios_base::binary);
     int out_count = 0;
     for (size_t i = 0; i < conjugation_list.size(); ++i) {
@@ -349,7 +350,7 @@ void Convert() {
   // Output conjugation suffix data index.
   {
     OutputFileStream ostream(
-        mozc::GetFlag(FLAGS_output_conjugation_index).c_str(),
+        absl::GetFlag(FLAGS_output_conjugation_index).c_str(),
         std::ios_base::out | std::ios_base::binary);
     ostream.write(reinterpret_cast<const char *>(conjugation_index.data()),
                   4 * conjugation_index.size());
@@ -358,7 +359,7 @@ void Convert() {
   // Output usage data.
   {
     OutputFileStream ostream(
-        mozc::GetFlag(FLAGS_output_usage_item_array).c_str(),
+        absl::GetFlag(FLAGS_output_usage_item_array).c_str(),
         std::ios_base::out | std::ios_base::binary);
     int32 usage_id = 0;
     for (const UsageItem &item : usage_entries) {
@@ -383,7 +384,7 @@ void Convert() {
       strs.emplace_back(kv.first);
     }
     SerializedStringArray::SerializeToFile(
-        strs, mozc::GetFlag(FLAGS_output_string_array));
+        strs, absl::GetFlag(FLAGS_output_string_array));
   }
 }
 
diff --git rewriter/katakana_promotion_rewriter.h rewriter/katakana_promotion_rewriter.h
index 5c7d4384b..197f2f5fc 100644
--- rewriter/katakana_promotion_rewriter.h
+++ rewriter/katakana_promotion_rewriter.h
@@ -30,9 +30,9 @@
 // Rewriter to promote katakana transliterated candidate for mobile devices.
 // For mobile, we do not provide the shortcut to input katakana transliterated
 // candidate.
-// If the katakana candiadte is not ranked high, users need to scroll candidate
+// If the katakana candidate is not ranked high, users need to scroll candidate
 // page and find katakana.
-// This rewriter promotes katakana candiate so that users can find katakana
+// This rewriter promotes katakana candidate so that users can find katakana
 // at first glance.
 
 #ifndef MOZC_REWRITER_KATAKANA_PROMOTION_REWRITER_H_
diff --git rewriter/merger_rewriter_test.cc rewriter/merger_rewriter_test.cc
index 828d71709..b47947f2a 100644
--- rewriter/merger_rewriter_test.cc
+++ rewriter/merger_rewriter_test.cc
@@ -31,7 +31,6 @@
 
 #include <string>
 
-#include "base/flags.h"
 #include "base/system_util.h"
 #include "config/config_handler.h"
 #include "converter/segments.h"
@@ -39,6 +38,7 @@
 #include "request/conversion_request.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 
@@ -103,7 +103,7 @@ class TestRewriter : public RewriterInterface {
 class MergerRewriterTest : public testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   }
 };
 
diff --git rewriter/normalization_rewriter.cc rewriter/normalization_rewriter.cc
index c95190063..f822bcffa 100644
--- rewriter/normalization_rewriter.cc
+++ rewriter/normalization_rewriter.cc
@@ -57,7 +57,7 @@ bool NormalizeCandidate(Segment::Candidate *candidate, CandidateType type) {
       TextNormalizer::NormalizeText(candidate->content_value, &content_value);
       break;
     default:
-      LOG(ERROR) << "unkown type";
+      LOG(ERROR) << "unknown type";
       return false;
   }
 
diff --git rewriter/normalization_rewriter_test.cc rewriter/normalization_rewriter_test.cc
index 4d1ee86de..e69397b86 100644
--- rewriter/normalization_rewriter_test.cc
+++ rewriter/normalization_rewriter_test.cc
@@ -31,12 +31,12 @@
 
 #include <string>
 
-#include "base/flags.h"
 #include "base/system_util.h"
 #include "converter/segments.h"
 #include "request/conversion_request.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace {
@@ -58,7 +58,7 @@ class NormalizationRewriterTest : public ::testing::Test {
   ~NormalizationRewriterTest() override = default;
 
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   }
 };
 
diff --git rewriter/number_rewriter.cc rewriter/number_rewriter.cc
index fd2e55856..24ab9acb5 100644
--- rewriter/number_rewriter.cc
+++ rewriter/number_rewriter.cc
@@ -449,7 +449,7 @@ bool NumberRewriter::Rewrite(const ConversionRequest &request,
 
   bool modified = false;
   // Radix conversion is done only for conversion mode.
-  // Showing radix candidates is annoying for an user.
+  // Showing radix candidates is annoying for a user.
   const bool exec_radix_conversion =
       (segments->conversion_segments_size() == 1 &&
        segments->request_type() == Segments::CONVERSION);
diff --git rewriter/number_rewriter_test.cc rewriter/number_rewriter_test.cc
index 7e95f7964..6801c2cff 100644
--- rewriter/number_rewriter_test.cc
+++ rewriter/number_rewriter_test.cc
@@ -96,7 +96,7 @@ bool HasDescription(const Segment &segment, const std::string &description) {
   return false;
 }
 
-// Find candiadte id
+// Find candidate id
 bool FindCandidateId(const Segment &segment, const std::string &value,
                      int *id) {
   for (size_t i = 0; i < segment.candidates_size(); ++i) {
@@ -835,7 +835,7 @@ TEST_F(NumberRewriterTest, SeparatedArabicsTest) {
 // - POS: GeneralNoun (not *Number*)
 // In this case, NumberRewriter should not clear
 // Segment::Candidate::USER_DICTIONARY bit in the base candidate.
-TEST_F(NumberRewriterTest, PreserveUserDictionaryAttibute) {
+TEST_F(NumberRewriterTest, PreserveUserDictionaryAttribute) {
   std::unique_ptr<NumberRewriter> number_rewriter(CreateNumberRewriter());
   {
     Segments segments;
diff --git rewriter/rewriter.cc rewriter/rewriter.cc
index 0b1c0b7e9..ed5f4dc9d 100644
--- rewriter/rewriter.cc
+++ rewriter/rewriter.cc
@@ -29,7 +29,6 @@
 
 #include "rewriter/rewriter.h"
 
-#include "base/flags.h"
 #include "base/logging.h"
 #include "converter/converter_interface.h"
 #include "data_manager/data_manager_interface.h"
@@ -63,11 +62,12 @@
 #include "rewriter/variants_rewriter.h"
 #include "rewriter/version_rewriter.h"
 #include "rewriter/zipcode_rewriter.h"
+#include "absl/flags/flag.h"
 #ifndef NO_USAGE_REWRITER
 #include "rewriter/usage_rewriter.h"
 #endif  // NO_USAGE_REWRITER
 
-MOZC_FLAG(bool, use_history_rewriter, true, "Use history rewriter or not.");
+ABSL_FLAG(bool, use_history_rewriter, true, "Use history rewriter or not.");
 
 namespace mozc {
 namespace {
@@ -104,7 +104,7 @@ RewriterImpl::RewriterImpl(const ConverterInterface *parent_converter,
   AddRewriter(new ZipcodeRewriter(&pos_matcher_));
   AddRewriter(new DiceRewriter);
 
-  if (mozc::GetFlag(FLAGS_use_history_rewriter)) {
+  if (absl::GetFlag(FLAGS_use_history_rewriter)) {
     AddRewriter(new UserBoundaryHistoryRewriter(parent_converter));
     AddRewriter(new UserSegmentHistoryRewriter(&pos_matcher_, pos_group));
   }
diff --git rewriter/rewriter_test.cc rewriter/rewriter_test.cc
index 2ec18ba6e..23609cf05 100644
--- rewriter/rewriter_test.cc
+++ rewriter/rewriter_test.cc
@@ -33,7 +33,6 @@
 #include <memory>
 #include <string>
 
-#include "base/flags.h"
 #include "base/system_util.h"
 #include "config/config_handler.h"
 #include "converter/converter_mock.h"
@@ -44,6 +43,7 @@
 #include "rewriter/rewriter_interface.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 namespace mozc {
@@ -68,7 +68,7 @@ size_t CommandCandidatesSize(const Segment &segment) {
 class RewriterTest : public ::testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     converter_mock_ = absl::make_unique<ConverterMock>();
     const testing::MockDataManager data_manager;
     pos_group_ = absl::make_unique<PosGroup>(data_manager.GetPosGroupData());
diff --git rewriter/single_kanji_rewriter_test.cc rewriter/single_kanji_rewriter_test.cc
index 53d3a20ef..c47670f78 100644
--- rewriter/single_kanji_rewriter_test.cc
+++ rewriter/single_kanji_rewriter_test.cc
@@ -33,7 +33,6 @@
 #include <memory>
 #include <string>
 
-#include "base/flags.h"
 #include "base/system_util.h"
 #include "base/util.h"
 #include "config/config_handler.h"
@@ -44,6 +43,7 @@
 #include "request/conversion_request.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 namespace mozc {
@@ -60,7 +60,7 @@ class SingleKanjiRewriterTest : public ::testing::Test {
   ~SingleKanjiRewriterTest() override = default;
 
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   }
 
   SingleKanjiRewriter *CreateSingleKanjiRewriter() const {
diff --git rewriter/symbol_rewriter.cc rewriter/symbol_rewriter.cc
index ab2a417d8..74cfc02ba 100644
--- rewriter/symbol_rewriter.cc
+++ rewriter/symbol_rewriter.cc
@@ -170,7 +170,7 @@ void SymbolRewriter::InsertCandidates(
     size_t default_offset, const SerializedDictionary::IterRange &range,
     bool context_sensitive, Segment *segment) {
   if (segment->candidates_size() == 0) {
-    LOG(WARNING) << "candiadtes_size is 0";
+    LOG(WARNING) << "candidates_size is 0";
     return;
   }
 
@@ -181,7 +181,7 @@ void SymbolRewriter::InsertCandidates(
   // register space to CharacterFormManager.
   ExpandSpace(segment);
 
-  // If the original candidates given by ImmutableConveter already
+  // If the original candidates given by ImmutableConverter already
   // include the target symbols, do assign description to these candidates.
   AddDescForCurrentCandidates(range, segment);
 
diff --git rewriter/symbol_rewriter_test.cc rewriter/symbol_rewriter_test.cc
index 29f5d9fca..6460c1e8b 100644
--- rewriter/symbol_rewriter_test.cc
+++ rewriter/symbol_rewriter_test.cc
@@ -32,7 +32,6 @@
 #include <memory>
 #include <string>
 
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/system_util.h"
 #include "base/util.h"
@@ -46,6 +45,7 @@
 #include "session/request_test_util.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 namespace mozc {
@@ -102,7 +102,7 @@ class SymbolRewriterTest : public ::testing::Test {
   ~SymbolRewriterTest() override = default;
 
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
 
     // We cannot use mock converter here because SymbolRewriter uses
     // ResizeSegment of converter implementation. However, SymbolRewriter is
diff --git rewriter/unicode_rewriter_test.cc rewriter/unicode_rewriter_test.cc
index e4af2c32f..aaffba108 100644
--- rewriter/unicode_rewriter_test.cc
+++ rewriter/unicode_rewriter_test.cc
@@ -34,7 +34,6 @@
 #include <memory>
 #include <string>
 
-#include "base/flags.h"
 #include "base/port.h"
 #include "base/system_util.h"
 #include "base/util.h"
@@ -48,6 +47,7 @@
 #include "request/conversion_request.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace {
@@ -87,7 +87,7 @@ class UnicodeRewriterTest : public ::testing::Test {
   ~UnicodeRewriterTest() override {}
 
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     engine_.reset(MockDataEngineFactory::Create());
   }
 
diff --git rewriter/usage_rewriter.cc rewriter/usage_rewriter.cc
index 53aec1d9e..f07a18922 100644
--- rewriter/usage_rewriter.cc
+++ rewriter/usage_rewriter.cc
@@ -139,7 +139,7 @@ std::string UsageRewriter::GetKanjiPrefixAndOneHiragana(
 UsageRewriter::UsageDictItemIterator
 UsageRewriter::LookupUnmatchedUsageHeuristically(
     const Segment::Candidate &candidate) const {
-  // We check Unknwon POS ("名詞,サ変接続") as well, since
+  // We check Unknown POS ("名詞,サ変接続") as well, since
   // target verbs/adjectives may be in web dictionary.
   if (!pos_matcher_.IsContentWordWithConjugation(candidate.lid) &&
       !pos_matcher_.IsUnknown(candidate.lid)) {
diff --git rewriter/usage_rewriter_test.cc rewriter/usage_rewriter_test.cc
index 197e3f944..f45ddf27a 100644
--- rewriter/usage_rewriter_test.cc
+++ rewriter/usage_rewriter_test.cc
@@ -34,7 +34,6 @@
 #include <memory>
 #include <string>
 
-#include "base/flags.h"
 #include "base/system_util.h"
 #include "config/config_handler.h"
 #include "converter/segments.h"
@@ -49,6 +48,7 @@
 #include "request/conversion_request.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 namespace mozc {
@@ -79,7 +79,7 @@ class UsageRewriterTest : public ::testing::Test {
   }
 
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     config::ConfigHandler::GetDefaultConfig(&config_);
 
     data_manager_ = absl::make_unique<testing::MockDataManager>();
diff --git rewriter/user_boundary_history_rewriter_test.cc rewriter/user_boundary_history_rewriter_test.cc
index 5e90260d8..b226c0f8a 100644
--- rewriter/user_boundary_history_rewriter_test.cc
+++ rewriter/user_boundary_history_rewriter_test.cc
@@ -34,7 +34,6 @@
 #include <string>
 
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/system_util.h"
 #include "config/config_handler.h"
 #include "converter/converter_mock.h"
@@ -43,6 +42,7 @@
 #include "request/conversion_request.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace {
@@ -83,7 +83,7 @@ class UserBoundaryHistoryRewriterTest : public ::testing::Test {
   UserBoundaryHistoryRewriterTest() { request_.set_config(&config_); }
 
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     config::ConfigHandler::GetDefaultConfig(&config_);
   }
 
@@ -114,7 +114,7 @@ class UserBoundaryHistoryRewriterTest : public ::testing::Test {
 TEST_F(UserBoundaryHistoryRewriterTest, CreateFile) {
   UserBoundaryHistoryRewriter rewriter(&mock());
   const std::string history_file =
-      mozc::GetFlag(FLAGS_test_tmpdir) + "/boundary.db";
+      absl::GetFlag(FLAGS_test_tmpdir) + "/boundary.db";
   EXPECT_TRUE(FileUtil::FileExists(history_file));
 }
 
@@ -227,8 +227,8 @@ TEST_F(UserBoundaryHistoryRewriterTest, NoInsertWhenIncognito) {
   SetIncognito(false);  // no_incognito when rewrite
   EXPECT_FALSE(rewriter.Rewrite(request_, &segments));
 
-  const std::string segments_rewrited_str = segments.DebugString();
-  EXPECT_EQ(segments_str, segments_rewrited_str);
+  const std::string segments_rewritten_str = segments.DebugString();
+  EXPECT_EQ(segments_str, segments_rewritten_str);
 }
 
 TEST_F(UserBoundaryHistoryRewriterTest, NoInsertWhenReadOnly) {
@@ -250,8 +250,8 @@ TEST_F(UserBoundaryHistoryRewriterTest, NoInsertWhenReadOnly) {
 
   EXPECT_FALSE(rewriter.Rewrite(request_, &segments));
 
-  const std::string segments_rewrited_str = segments.DebugString();
-  EXPECT_EQ(segments_str, segments_rewrited_str);
+  const std::string segments_rewritten_str = segments.DebugString();
+  EXPECT_EQ(segments_str, segments_rewritten_str);
 }
 
 TEST_F(UserBoundaryHistoryRewriterTest, NoInsertWhenDisableUserHistory) {
@@ -273,8 +273,8 @@ TEST_F(UserBoundaryHistoryRewriterTest, NoInsertWhenDisableUserHistory) {
 
   EXPECT_FALSE(rewriter.Rewrite(request_, &segments));
 
-  const std::string segments_rewrited_str = segments.DebugString();
-  EXPECT_EQ(segments_str, segments_rewrited_str);
+  const std::string segments_rewritten_str = segments.DebugString();
+  EXPECT_EQ(segments_str, segments_rewritten_str);
 }
 
 TEST_F(UserBoundaryHistoryRewriterTest, NoInsertWhenNotResized) {
@@ -296,8 +296,8 @@ TEST_F(UserBoundaryHistoryRewriterTest, NoInsertWhenNotResized) {
 
   EXPECT_FALSE(rewriter.Rewrite(request_, &segments));
 
-  const std::string segments_rewrited_str = segments.DebugString();
-  EXPECT_EQ(segments_str, segments_rewrited_str);
+  const std::string segments_rewritten_str = segments.DebugString();
+  EXPECT_EQ(segments_str, segments_rewritten_str);
 }
 
 TEST_F(UserBoundaryHistoryRewriterTest, NoRewriteAfterClear) {
@@ -322,8 +322,8 @@ TEST_F(UserBoundaryHistoryRewriterTest, NoRewriteAfterClear) {
   const std::string segments_str = segments.DebugString();
   EXPECT_FALSE(rewriter.Rewrite(request_, &segments));
 
-  const std::string segments_rewrited_str = segments.DebugString();
-  EXPECT_EQ(segments_str, segments_rewrited_str);
+  const std::string segments_rewritten_str = segments.DebugString();
+  EXPECT_EQ(segments_str, segments_rewritten_str);
 }
 
 TEST_F(UserBoundaryHistoryRewriterTest, NoRewriteWhenIncognito) {
@@ -346,8 +346,8 @@ TEST_F(UserBoundaryHistoryRewriterTest, NoRewriteWhenIncognito) {
   SetIncognito(true);
   EXPECT_FALSE(rewriter.Rewrite(request_, &segments));
 
-  const std::string segments_rewrited_str = segments.DebugString();
-  EXPECT_EQ(segments_str, segments_rewrited_str);
+  const std::string segments_rewritten_str = segments.DebugString();
+  EXPECT_EQ(segments_str, segments_rewritten_str);
 }
 
 TEST_F(UserBoundaryHistoryRewriterTest, NoRewriteWhenNoHistory) {
@@ -370,8 +370,8 @@ TEST_F(UserBoundaryHistoryRewriterTest, NoRewriteWhenNoHistory) {
   SetLearningLevel(config::Config::NO_HISTORY);
   EXPECT_FALSE(rewriter.Rewrite(request_, &segments));
 
-  const std::string segments_rewrited_str = segments.DebugString();
-  EXPECT_EQ(segments_str, segments_rewrited_str);
+  const std::string segments_rewritten_str = segments.DebugString();
+  EXPECT_EQ(segments_str, segments_rewritten_str);
 }
 
 TEST_F(UserBoundaryHistoryRewriterTest, NoRewriteWhenDisabledUserHistory) {
@@ -393,8 +393,8 @@ TEST_F(UserBoundaryHistoryRewriterTest, NoRewriteWhenDisabledUserHistory) {
   const std::string segments_str = segments.DebugString();
   EXPECT_FALSE(rewriter.Rewrite(request_, &segments));
 
-  const std::string segments_rewrited_str = segments.DebugString();
-  EXPECT_EQ(segments_str, segments_rewrited_str);
+  const std::string segments_rewritten_str = segments.DebugString();
+  EXPECT_EQ(segments_str, segments_rewritten_str);
 }
 
 TEST_F(UserBoundaryHistoryRewriterTest, NoRewriteWhenAlreadyResized) {
@@ -417,7 +417,7 @@ TEST_F(UserBoundaryHistoryRewriterTest, NoRewriteWhenAlreadyResized) {
   const std::string segments_str = segments.DebugString();
   EXPECT_FALSE(rewriter.Rewrite(request_, &segments));
 
-  const std::string segments_rewrited_str = segments.DebugString();
-  EXPECT_EQ(segments_str, segments_rewrited_str);
+  const std::string segments_rewritten_str = segments.DebugString();
+  EXPECT_EQ(segments_str, segments_rewritten_str);
 }
 }  // namespace mozc
diff --git rewriter/user_dictionary_rewriter_test.cc rewriter/user_dictionary_rewriter_test.cc
index f54ddc22b..7cccdb11d 100644
--- rewriter/user_dictionary_rewriter_test.cc
+++ rewriter/user_dictionary_rewriter_test.cc
@@ -33,7 +33,6 @@
 #include <string>
 #include <vector>
 
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/system_util.h"
 #include "base/util.h"
@@ -41,6 +40,7 @@
 #include "request/conversion_request.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 
@@ -85,7 +85,7 @@ class UserDictionaryRewriterTest : public testing::Test {
   ~UserDictionaryRewriterTest() override {}
 
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   }
 
   void TearDown() override {}
diff --git rewriter/user_segment_history_rewriter.cc rewriter/user_segment_history_rewriter.cc
index 5d1f0bd24..d4e3448b2 100644
--- rewriter/user_segment_history_rewriter.cc
+++ rewriter/user_segment_history_rewriter.cc
@@ -142,10 +142,10 @@ class ScoreTypeCompare {
   }
 };
 
-// return the first candiadte which has "BEST_CANDIDATE" attribute
+// return the first candidate which has "BEST_CANDIDATE" attribute
 inline int GetDefaultCandidateIndex(const Segment &segment) {
   // Check up to kMaxRerankSize + 1 candidates because candidate with
-  // BEST_CANDIATE is highly possibly in that range (http://b/9992330).
+  // BEST_CANDIDATE is highly possibly in that range (http://b/9992330).
   const int size =
       static_cast<int>(std::min(segment.candidates_size(), kMaxRerankSize + 1));
   for (int i = 0; i < size; ++i) {
@@ -690,7 +690,7 @@ void UserSegmentHistoryRewriter::RememberFirstCandidate(
   const std::string &all_key = seg.key();
   const std::string &content_key = candidate.content_key;
 
-  // even if the candiate was the top (default) candidate,
+  // even if the candidate was the top (default) candidate,
   // ERANKED will be set when user changes the ranking
   const bool force_insert =
       ((candidate.attributes & Segment::Candidate::RERANKED) != 0);
diff --git rewriter/user_segment_history_rewriter_test.cc rewriter/user_segment_history_rewriter_test.cc
index c3271a7d8..d34069bbe 100644
--- rewriter/user_segment_history_rewriter_test.cc
+++ rewriter/user_segment_history_rewriter_test.cc
@@ -35,7 +35,6 @@
 #include "base/clock.h"
 #include "base/clock_mock.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/number_util.h"
 #include "base/system_util.h"
@@ -52,6 +51,7 @@
 #include "rewriter/variants_rewriter.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 namespace mozc {
@@ -113,7 +113,7 @@ class UserSegmentHistoryRewriterTest : public ::testing::Test {
   UserSegmentHistoryRewriterTest() { request_.set_config(&config_); }
 
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
 
     ConfigHandler::GetDefaultConfig(&config_);
     for (int i = 0; i < config_.character_form_rules_size(); ++i) {
@@ -181,7 +181,7 @@ TEST_F(UserSegmentHistoryRewriterTest, CreateFile) {
   std::unique_ptr<UserSegmentHistoryRewriter> rewriter(
       CreateUserSegmentHistoryRewriter());
   const std::string history_file =
-      FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir), "/segment.db");
+      FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir), "/segment.db");
   EXPECT_TRUE(FileUtil::FileExists(history_file));
 }
 
diff --git rewriter/variants_rewriter.cc rewriter/variants_rewriter.cc
index 51cf50a09..9082b9461 100644
--- rewriter/variants_rewriter.cc
+++ rewriter/variants_rewriter.cc
@@ -313,7 +313,7 @@ bool VariantsRewriter::RewriteSegment(RewriteType type, Segment *seg) const {
     if (original_candidate->attributes &
         Segment::Candidate::NO_VARIANTS_EXPANSION) {
       SetDescriptionForCandidate(pos_matcher_, original_candidate);
-      VLOG(1) << "Canidate has NO_NORMALIZATION node";
+      VLOG(1) << "Candidate has NO_NORMALIZATION node";
       continue;
     }
 
diff --git rewriter/variants_rewriter_test.cc rewriter/variants_rewriter_test.cc
index 7b92e09ec..78bef9ed5 100644
--- rewriter/variants_rewriter_test.cc
+++ rewriter/variants_rewriter_test.cc
@@ -426,7 +426,7 @@ TEST_F(VariantsRewriterTest, SetDescriptionForCandidate) {
     candidate.content_key = "ねずみ";
     candidate.description = "絵文字";
     VariantsRewriter::SetDescriptionForCandidate(pos_matcher_, &candidate);
-    // "絵文字 <機種依存文字>" for Desktop, "絵文字 <機種依存>" for Andorid
+    // "絵文字 <機種依存文字>" for Desktop, "絵文字 <機種依存>" for Android
     std::string expected(
         "絵文字"
         " ");
diff --git rewriter/version_rewriter_test.cc rewriter/version_rewriter_test.cc
index 53ea65640..c7b91c5d1 100644
--- rewriter/version_rewriter_test.cc
+++ rewriter/version_rewriter_test.cc
@@ -32,7 +32,6 @@
 #include <cstddef>
 #include <string>
 
-#include "base/flags.h"
 #include "base/system_util.h"
 #include "base/util.h"
 #include "config/config_handler.h"
@@ -41,6 +40,7 @@
 #include "request/conversion_request.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace {
@@ -52,7 +52,7 @@ const char *kDummyDataVersion = "dataversion";
 class VersionRewriterTest : public ::testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   }
 
   static void AddSegment(const std::string &key, const std::string &value,
diff --git server/BUILD server/BUILD
index c65968856..af14825f9 100644
--- server/BUILD
+++ server/BUILD
@@ -64,7 +64,6 @@ cc_library_mozc(
     deps = [
         "//base",
         "//base:crash_report_handler",
-        "//base:flags",
         "//base:init_mozc",
         "//base:logging",
         "//base:port",
@@ -85,7 +84,6 @@ cc_binary_mozc(
     srcs = ["mozc_rpc_server_main.cc"],
     deps = [
         "//base",
-        "//base:flags",
         "//base:init_mozc",
         "//base:singleton",
         "//base:system_util",
diff --git server/cache_service_manager.cc server/cache_service_manager.cc
index 5fcd064f3..48cbf045a 100644
--- server/cache_service_manager.cc
+++ server/cache_service_manager.cc
@@ -148,14 +148,14 @@ bool DeserializeFromBase64WString(const std::wstring &src,
 //  - It turns out w/o any error that the cache service is not installed.
 //    In this case, |handle| owns a NULL handle.
 // Otherwise, returns false.
-bool GetCacheService(DWORD service_controler_rights, DWORD service_rights,
+bool GetCacheService(DWORD service_controller_rights, DWORD service_rights,
                      ScopedSCHandle *handle) {
   if (NULL == handle) {
     return false;
   }
 
   ScopedSCHandle sc_handle(
-      ::OpenSCManager(NULL, NULL, service_controler_rights));
+      ::OpenSCManager(NULL, NULL, service_controller_rights));
   if (NULL == sc_handle.get()) {
     LOG(ERROR) << "OpenSCManager failed: " << ::GetLastError();
     return false;
@@ -314,7 +314,7 @@ bool RestoreStateInternal(const cache_service::Win32ServiceState &state) {
 
   const bool now_running = IsServiceRunning(service_handle);
 
-  // If the service was runnning and is not running now, start it unless the
+  // If the service was running and is not running now, start it unless the
   // load type is not DISABLED.
   if (state.running() && !now_running &&
       (state.load_type() != cache_service::Win32ServiceState::DISABLED)) {
@@ -326,7 +326,7 @@ bool RestoreStateInternal(const cache_service::Win32ServiceState &state) {
       }
     }
     return StartServiceInternal(service_handle, arguments);
-    // If the service is now runnning and was not running, stop it.
+    // If the service is now running and was not running, stop it.
   } else if (!state.running() && now_running) {
     return StopService(service_handle);
     // Nothing to do.
@@ -407,7 +407,7 @@ bool CacheServiceManager::IsEnabled() {
   }
 
   // This byte array will contain both QUERY_SERVICE_CONFIG and some
-  // string buffers which are reffered by corresponding members of
+  // string buffers which are referred by corresponding members of
   // QUERY_SERVICE_CONFIG.  We have to keep the array until we complete
   // all tasks which use the contents of QUERY_SERVICE_CONFIG.
   std::unique_ptr<char[]> buffer;
@@ -539,7 +539,7 @@ bool CacheServiceManager::BackupStateAsString(std::wstring *result) {
     state.set_running(true);
   } else {
     // This byte array will contain both QUERY_SERVICE_CONFIG and some
-    // string buffers which are reffered by corresponding members of
+    // string buffers which are referred by corresponding members of
     // QUERY_SERVICE_CONFIG.  We have to keep the array until we complete
     // all tasks which use the contents of QUERY_SERVICE_CONFIG.
     std::unique_ptr<char[]> buffer;
diff --git server/mozc_cache_service.rc server/mozc_cache_service.rc
index aa89ce828..9bb7c8d95 100644
Binary files server/mozc_cache_service.rc and server/mozc_cache_service.rc differ
diff --git server/mozc_rpc_server_main.cc server/mozc_rpc_server_main.cc
index 296e0373f..6160b6cd2 100644
--- server/mozc_rpc_server_main.cc
+++ server/mozc_rpc_server_main.cc
@@ -27,7 +27,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#include "absl/flags/flag.h"
 #ifdef OS_WIN
 #include <windows.h>
 #include <ws2tcpip.h>
@@ -47,7 +46,6 @@ using ssize_t = SSIZE_T;
 #include <string>
 #include <vector>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/singleton.h"
 #include "base/system_util.h"
@@ -56,14 +54,15 @@ using ssize_t = SSIZE_T;
 #include "session/random_keyevents_generator.h"
 #include "session/session_handler.h"
 #include "session/session_usage_observer.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, host, "localhost", "server host name");
-MOZC_FLAG(bool, server, true, "server mode");
-MOZC_FLAG(bool, client, false, "client mode");
-MOZC_FLAG(int32, client_test_size, 100, "client test size");
-MOZC_FLAG(int32, port, 8000, "port of RPC server");
-MOZC_FLAG(int32, rpc_timeout, 60000, "timeout");
-MOZC_FLAG(string, user_profile_directory, "", "user profile directory");
+ABSL_FLAG(std::string, host, "localhost", "server host name");
+ABSL_FLAG(bool, server, true, "server mode");
+ABSL_FLAG(bool, client, false, "client mode");
+ABSL_FLAG(int32, client_test_size, 100, "client test size");
+ABSL_FLAG(int32, port, 8000, "port of RPC server");
+ABSL_FLAG(int32, rpc_timeout, 60000, "timeout");
+ABSL_FLAG(std::string, user_profile_directory, "", "user profile directory");
 
 namespace mozc {
 
@@ -144,7 +143,7 @@ class RPCServer {
 #endif
 
     ::memset(&sin, 0, sizeof(sin));
-    sin.sin_port = htons(mozc::GetFlag(FLAGS_port));
+    sin.sin_port = htons(absl::GetFlag(FLAGS_port));
     sin.sin_family = AF_INET;
     sin.sin_addr.s_addr = htonl(INADDR_ANY);
 
@@ -182,7 +181,7 @@ class RPCServer {
       uint32 request_size = 0;
       // Receive the size of data.
       if (!Recv(client_socket, reinterpret_cast<char *>(&request_size),
-                sizeof(request_size), mozc::GetFlag(FLAGS_rpc_timeout))) {
+                sizeof(request_size), absl::GetFlag(FLAGS_rpc_timeout))) {
         LOG(ERROR) << "Cannot receive request_size header.";
         CloseSocket(client_socket);
         continue;
@@ -194,7 +193,7 @@ class RPCServer {
       // Receive the body of serialized protobuf.
       std::unique_ptr<char[]> request_str(new char[request_size]);
       if (!Recv(client_socket, request_str.get(), request_size,
-                mozc::GetFlag(FLAGS_rpc_timeout))) {
+                absl::GetFlag(FLAGS_rpc_timeout))) {
         LOG(ERROR) << "cannot receive body of request.";
         CloseSocket(client_socket);
         continue;
@@ -220,9 +219,9 @@ class RPCServer {
       output_size = htonl(output_size);
 
       if (!Send(client_socket, reinterpret_cast<char *>(&output_size),
-                sizeof(output_size), mozc::GetFlag(FLAGS_rpc_timeout)) ||
+                sizeof(output_size), absl::GetFlag(FLAGS_rpc_timeout)) ||
           !Send(client_socket, output_str.data(), output_str.size(),
-                mozc::GetFlag(FLAGS_rpc_timeout))) {
+                absl::GetFlag(FLAGS_rpc_timeout))) {
         LOG(ERROR) << "Cannot send reply.";
       }
 
@@ -284,8 +283,8 @@ class RPCClient {
     hints.ai_socktype = SOCK_STREAM;
     hints.ai_family = AF_INET;
 
-    const std::string port_str = std::to_string(mozc::GetFlag(FLAGS_port));
-    CHECK_EQ(::getaddrinfo(mozc::GetFlag(FLAGS_host).c_str(), port_str.c_str(),
+    const std::string port_str = std::to_string(absl::GetFlag(FLAGS_port));
+    CHECK_EQ(::getaddrinfo(absl::GetFlag(FLAGS_host).c_str(), port_str.c_str(),
                            &hints, &res),
              0)
         << "getaddrinfo failed";
@@ -304,20 +303,20 @@ class RPCClient {
     request_size = htonl(request_size);
 
     CHECK(Send(client_socket, reinterpret_cast<char *>(&request_size),
-               sizeof(request_size), mozc::GetFlag(FLAGS_rpc_timeout)));
+               sizeof(request_size), absl::GetFlag(FLAGS_rpc_timeout)));
     CHECK(Send(client_socket, request_str.data(), request_str.size(),
-               mozc::GetFlag(FLAGS_rpc_timeout)));
+               absl::GetFlag(FLAGS_rpc_timeout)));
 
     uint32 output_size = 0;
     CHECK(Recv(client_socket, reinterpret_cast<char *>(&output_size),
-               sizeof(output_size), mozc::GetFlag(FLAGS_rpc_timeout)));
+               sizeof(output_size), absl::GetFlag(FLAGS_rpc_timeout)));
     output_size = ntohl(output_size);
     CHECK_GT(output_size, 0);
     CHECK_LT(output_size, kMaxOutputSize);
 
     std::unique_ptr<char[]> output_str(new char[output_size]);
     CHECK(Recv(client_socket, output_str.get(), output_size,
-               mozc::GetFlag(FLAGS_rpc_timeout)));
+               absl::GetFlag(FLAGS_rpc_timeout)));
 
     CHECK(output->ParseFromArray(output_str.get(), output_size));
 
@@ -355,17 +354,17 @@ int main(int argc, char *argv[]) {
 
   mozc::ScopedWSAData wsadata;
 
-  if (!mozc::GetFlag(FLAGS_user_profile_directory).empty()) {
+  if (!absl::GetFlag(FLAGS_user_profile_directory).empty()) {
     LOG(INFO) << "Setting user profile directory to "
-              << mozc::GetFlag(FLAGS_user_profile_directory);
+              << absl::GetFlag(FLAGS_user_profile_directory);
     mozc::SystemUtil::SetUserProfileDirectory(
-        mozc::GetFlag(FLAGS_user_profile_directory));
+        absl::GetFlag(FLAGS_user_profile_directory));
   }
 
-  if (mozc::GetFlag(FLAGS_client)) {
+  if (absl::GetFlag(FLAGS_client)) {
     mozc::RPCClient client;
     CHECK(client.CreateSession());
-    for (int n = 0; n < mozc::GetFlag(FLAGS_client_test_size); ++n) {
+    for (int n = 0; n < absl::GetFlag(FLAGS_client_test_size); ++n) {
       std::vector<mozc::commands::KeyEvent> keys;
       mozc::session::RandomKeyEventsGenerator::GenerateSequence(&keys);
       for (size_t i = 0; i < keys.size(); ++i) {
@@ -377,7 +376,7 @@ int main(int argc, char *argv[]) {
     }
     CHECK(client.DeleteSession());
     return 0;
-  } else if (mozc::GetFlag(FLAGS_server)) {
+  } else if (absl::GetFlag(FLAGS_server)) {
     mozc::RPCServer server;
     server.Loop();
   } else {
diff --git server/mozc_server.cc server/mozc_server.cc
index 228344f9d..bd3ecd39c 100644
--- server/mozc_server.cc
+++ server/mozc_server.cc
@@ -29,8 +29,6 @@
 
 #include "server/mozc_server.h"
 
-#include "absl/flags/flag.h"
-
 #ifdef OS_WIN
 #include <windows.h>
 #endif
@@ -40,7 +38,6 @@
 #include <string>
 
 #include "base/crash_report_handler.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/process_mutex.h"
@@ -50,8 +47,10 @@
 #include "base/util.h"
 #include "config/stats_config_util.h"
 #include "session/session_server.h"
+#include "absl/flags/declare.h"
+#include "absl/flags/flag.h"
 
-MOZC_DECLARE_FLAG(bool, restricted);  // in SessionHandler
+ABSL_DECLARE_FLAG(bool, restricted);  // in SessionHandler
 
 namespace {
 mozc::SessionServer *g_session_server = NULL;
@@ -92,7 +91,7 @@ void InitMozcAndMozcServer(const char *arg0, int *argc, char ***argv,
 
   if (run_level == mozc::RunLevel::RESTRICTED) {
     VLOG(1) << "Mozc server starts with timeout mode";
-    mozc::SetFlag(&FLAGS_restricted, true);
+    absl::SetFlag(&FLAGS_restricted, true);
   }
 }
 
diff --git server/mozc_server.rc server/mozc_server.rc
index fd97c8767..d78370110 100644
Binary files server/mozc_server.rc and server/mozc_server.rc differ
diff --git session/BUILD session/BUILD
index cc47ec3cf..07c7cf81e 100644
--- session/BUILD
+++ session/BUILD
@@ -73,7 +73,6 @@ cc_library_mozc(
         ":session_converter_interface",
         ":session_usage_stats_util",
         "//base",
-        "//base:flags",
         "//base:logging",
         "//base:port",
         "//base:text_normalizer",
@@ -90,6 +89,7 @@ cc_library_mozc(
         "//session/internal:session_output",
         "//transliteration",
         "//usage_stats",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -103,7 +103,6 @@ cc_test_mozc(
         ":request_test_util",
         ":session_converter",
         "//base",
-        "//base:flags",
         "//base:logging",
         "//base:system_util",
         "//base:util",
@@ -123,6 +122,7 @@ cc_test_mozc(
         "//transliteration",
         "//usage_stats",
         "//usage_stats:usage_stats_testing_util",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
@@ -136,7 +136,6 @@ cc_test_mozc(
         ":session_converter",
         "//base",
         "//base:clock",
-        "//base:flags",
         "//base:port",
         "//base:system_util",
         "//base:util",
@@ -148,6 +147,7 @@ cc_test_mozc(
         "//protocol:commands_proto",
         "//protocol:config_proto",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -251,7 +251,6 @@ cc_test_mozc(
         ":session_handler",
         "//base",
         "//base:file_util",
-        "//base:flags",
         "//base:logging",
         "//base:port",
         "//base:system_util",
@@ -269,6 +268,7 @@ cc_test_mozc(
         "//session/internal:ime_context",
         "//session/internal:keymap",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
@@ -341,7 +341,7 @@ cc_library_mozc(
         "//usage_stats",
         "@com_google_absl//absl/memory",
     ] + [
-        "//base:flags",
+        "@com_google_absl//absl/flags:flag",
         "//base:logging",
         "//base:port",
         "//base:singleton",
@@ -371,7 +371,6 @@ cc_library_mozc(
         "//base",
         "//base:config_file_stream",
         "//base:file_util",
-        "//base:flags",
         "//base:logging",
         "//base:port",
         "//base:system_util",
@@ -389,6 +388,7 @@ cc_library_mozc(
         "//testing",
         "//testing:gunit_prod",
         "//usage_stats:usage_stats_testing_util",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -405,7 +405,6 @@ cc_test_mozc(
         ":session_handler_test_util",
         "//base",
         "//base:clock_mock",
-        "//base:flags",
         "//base:port",
         "//base:stopwatch",
         "//base:util",
@@ -421,6 +420,7 @@ cc_test_mozc(
         "//testing:gunit_main",
         "//usage_stats",
         "//usage_stats:usage_stats_testing_util",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
@@ -456,10 +456,10 @@ cc_test_mozc(
     deps = [
         ":session_server",
         "//base",
-        "//base:flags",
         "//base:scheduler",
         "//base:system_util",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -503,7 +503,6 @@ cc_binary_mozc(
         "//base",
         "//base:file_stream",
         "//base:file_util",
-        "//base:flags",
         "//base:init_mozc",
         "//base:logging",
         "//base:port",
@@ -514,6 +513,7 @@ cc_binary_mozc(
         "//engine:engine_interface",
         "//protocol:commands_proto",
         "//protocol:config_proto",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
@@ -524,9 +524,9 @@ cc_binary_mozc(
     copts = ["$(STACK_FRAME_UNLIMITED)"],  # session_server_main.cc
     deps = [
         ":session_server",
-        "//base:flags",
         "//base:init_mozc",
         "//protocol:commands_proto",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings:str_format",
     ],
 )
@@ -599,7 +599,6 @@ cc_test_mozc(
         ":session_usage_observer",
         "//base",
         "//base:clock_mock",
-        "//base:flags",
         "//base:logging",
         "//base:scheduler",
         "//base:scheduler_stub",
@@ -612,6 +611,7 @@ cc_test_mozc(
         "//usage_stats",
         "//usage_stats:usage_stats_proto",
         "//usage_stats:usage_stats_testing_util",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
@@ -782,7 +782,6 @@ cc_binary_mozc(
     deps = [
         ":session_handler_tool",
         "//base:file_stream",
-        "//base:flags",
         "//base:init_mozc",
         "//base:status",
         "//base:system_util",
@@ -791,6 +790,7 @@ cc_binary_mozc(
         "//data_manager/oss:oss_data_manager",
         "//engine",
         "//protocol:commands_proto",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
diff --git session/ime_switch_util.h session/ime_switch_util.h
index c7246e84e..12e27ab66 100644
--- session/ime_switch_util.h
+++ session/ime_switch_util.h
@@ -51,7 +51,7 @@ class ImeSwitchUtil {
   // Returns true if 'key' is assigned for any command in direct mode.
   // We want to know this configuration before starting mozc server,
   // because we use this config to start mozc server.
-  // Please call this fuction only when the server is not runnning.
+  // Please call this fuction only when the server is not running.
   static bool IsDirectModeCommand(const commands::KeyEvent &key);
 
   static void ReloadConfig(const Config &config);
diff --git session/internal/BUILD session/internal/BUILD
index f33e8bb6e..4dfb9019d 100644
--- session/internal/BUILD
+++ session/internal/BUILD
@@ -187,13 +187,13 @@ cc_test_mozc(
         ":keymap",
         ":keymap_factory",
         "//base:config_file_stream",
-        "//base:flags",
         "//base:system_util",
         "//composer:key_parser",
         "//config:config_handler",
         "//protocol:commands_proto",
         "//protocol:config_proto",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
diff --git session/internal/key_event_transformer.cc session/internal/key_event_transformer.cc
index 79ab34c5e..9ed550dd5 100644
--- session/internal/key_event_transformer.cc
+++ session/internal/key_event_transformer.cc
@@ -157,7 +157,7 @@ bool KeyEventTransformer::TransformKeyEventForNumpad(
   }
 
   // All key event except for KeyEvent::SEPARATOR should have key code
-  // and it's value should represent a ASCII character since it is generated
+  // and its value should represent a ASCII character since it is generated
   // from numpad key.
   DCHECK(key_event->has_key_code());
   const uint32 key_code = key_event->key_code();
diff --git session/internal/keymap_interface.h session/internal/keymap_interface.h
index 91840a4d6..e2a585c18 100644
--- session/internal/keymap_interface.h
+++ session/internal/keymap_interface.h
@@ -102,7 +102,7 @@ struct CompositionState {
     INSERT_ALTERNATE_SPACE,
     INSERT_HALF_SPACE,   // Input half-width space
     INSERT_FULL_SPACE,   // Input full-width space
-    CANCEL,              // Move to Precomposition stauts.
+    CANCEL,              // Move to Precomposition status.
     CANCEL_AND_IME_OFF,  // Cancel composition and turn off IME
     UNDO,
     MOVE_CURSOR_LEFT,
diff --git session/internal/keymap_test.cc session/internal/keymap_test.cc
index 76ed26f1b..90f07e17c 100644
--- session/internal/keymap_test.cc
+++ session/internal/keymap_test.cc
@@ -36,7 +36,6 @@
 #include <vector>
 
 #include "base/config_file_stream.h"
-#include "base/flags.h"
 #include "base/system_util.h"
 #include "composer/key_parser.h"
 #include "config/config_handler.h"
@@ -46,6 +45,7 @@
 #include "session/internal/keymap_factory.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace keymap {
@@ -53,7 +53,7 @@ namespace keymap {
 class KeyMapTest : public testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   }
 
   bool isInputModeXCommandSupported() const {
diff --git session/session.cc session/session.cc
index 878f1ec9d..d7d9cc61b 100644
--- session/session.cc
+++ session/session.cc
@@ -1443,7 +1443,7 @@ bool Session::InsertCharacter(commands::Command *command) {
   bool should_commit = (context_->state() == ImeContext::CONVERSION);
 
   if (context_->GetRequest().space_on_alphanumeric() ==
-          commands::Request::SPACE_OR_CONVERT_COMMITING_COMPOSITION &&
+          commands::Request::SPACE_OR_CONVERT_COMMITTING_COMPOSITION &&
       context_->state() == ImeContext::COMPOSITION &&
       // TODO(komatsu): Support FullWidthSpace
       Util::EndsWith(composition, " ")) {
@@ -2289,7 +2289,7 @@ bool Session::Convert(commands::Command *command) {
         return Commit(command);
       } else {
         // SPACE_OR_CONVERT_KEEPING_COMPOSITION or
-        // SPACE_OR_CONVERT_COMMITING_COMPOSITION.
+        // SPACE_OR_CONVERT_COMMITTING_COMPOSITION.
 
         // If the last character is not space, space is inserted to the
         // composition.
diff --git session/session.h session/session.h
index 6d3e09dd8..08748d2c2 100644
--- session/session.h
+++ session/session.h
@@ -266,7 +266,7 @@ class Session : public SessionInterface {
   // return 0 (default value) if no command is executed in this session.
   uint64 last_command_time() const override;
 
-  // TODO(komatsu): delete this funciton.
+  // TODO(komatsu): delete this function.
   // For unittest only
   mozc::composer::Composer *get_internal_composer_only_for_unittest();
 
diff --git session/session_client_main.cc session/session_client_main.cc
index 6b787cbe0..548d336d2 100644
--- session/session_client_main.cc
+++ session/session_client_main.cc
@@ -33,7 +33,6 @@
 
 #include "base/file_stream.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/port.h"
@@ -44,11 +43,12 @@
 #include "engine/engine_interface.h"
 #include "protocol/commands.pb.h"
 #include "session/session.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
-MOZC_FLAG(string, input, "", "Input file");
-MOZC_FLAG(string, output, "", "Output file");
-MOZC_FLAG(string, profile_dir, "", "Profile dir");
+ABSL_FLAG(std::string, input, "", "Input file");
+ABSL_FLAG(std::string, output, "", "Output file");
+ABSL_FLAG(std::string, profile_dir, "", "Profile dir");
 
 namespace mozc {
 
@@ -94,9 +94,9 @@ int main(int argc, char **argv) {
   std::istream *input = nullptr;
   std::ostream *output = nullptr;
 
-  const std::string flags_profile_dir = mozc::GetFlag(FLAGS_profile_dir);
-  const std::string flags_input = mozc::GetFlag(FLAGS_input);
-  const std::string flags_output = mozc::GetFlag(FLAGS_output);
+  const std::string flags_profile_dir = absl::GetFlag(FLAGS_profile_dir);
+  const std::string flags_input = absl::GetFlag(FLAGS_input);
+  const std::string flags_output = absl::GetFlag(FLAGS_output);
 
   if (!flags_profile_dir.empty()) {
     // TODO(komatsu): Make a tmp dir and use it.
diff --git session/session_converter.cc session/session_converter.cc
index a0a4e8b0c..77ae3a28e 100644
--- session/session_converter.cc
+++ session/session_converter.cc
@@ -35,7 +35,6 @@
 #include <limits>
 #include <string>
 
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/port.h"
 #include "base/text_normalizer.h"
@@ -53,6 +52,7 @@
 #include "session/session_usage_stats_util.h"
 #include "transliteration/transliteration.h"
 #include "usage_stats/usage_stats.h"
+#include "absl/flags/flag.h"
 
 using mozc::usage_stats::UsageStats;
 
@@ -62,7 +62,7 @@ const bool kDefaultUseActualConverterForRealtimeConversion = false;
 const bool kDefaultUseActualConverterForRealtimeConversion = true;
 #endif  // OS_ANDROID
 
-MOZC_FLAG(bool, use_actual_converter_for_realtime_conversion,
+ABSL_FLAG(bool, use_actual_converter_for_realtime_conversion,
           kDefaultUseActualConverterForRealtimeConversion,
           "If true, use the actual (non-immutable) converter for real "
           "time conversion.");
@@ -428,7 +428,7 @@ bool SessionConverter::SuggestWithPreferences(
     conversion_request.set_create_partial_candidates(
         request_->auto_partial_suggestion());
     conversion_request.set_use_actual_converter_for_realtime_conversion(
-        mozc::GetFlag(FLAGS_use_actual_converter_for_realtime_conversion));
+        absl::GetFlag(FLAGS_use_actual_converter_for_realtime_conversion));
     if (!converter_->StartSuggestionForRequest(conversion_request,
                                                segments_.get())) {
       // TODO(komatsu): Because suggestion is a prefix search, once
@@ -504,7 +504,7 @@ bool SessionConverter::PredictWithPreferences(
   if (predict_expand || predict_first) {
     ConversionRequest conversion_request(&composer, request_, config_);
     conversion_request.set_use_actual_converter_for_realtime_conversion(
-        mozc::GetFlag(FLAGS_use_actual_converter_for_realtime_conversion));
+        absl::GetFlag(FLAGS_use_actual_converter_for_realtime_conversion));
     if (!converter_->StartPredictionForRequest(conversion_request,
                                                segments_.get())) {
       LOG(WARNING) << "StartPredictionForRequest() failed";
@@ -576,7 +576,7 @@ bool SessionConverter::ExpandSuggestionWithPreferences(
     conversion_request.set_create_partial_candidates(
         request_->auto_partial_suggestion());
     conversion_request.set_use_actual_converter_for_realtime_conversion(
-        mozc::GetFlag(FLAGS_use_actual_converter_for_realtime_conversion));
+        absl::GetFlag(FLAGS_use_actual_converter_for_realtime_conversion));
     // This is abuse of StartPrediction().
     // TODO(matsuzakit or yamaguchi): Add ExpandSuggestion method
     //    to Converter class.
diff --git session/session_converter.h session/session_converter.h
index b1ac98895..fe5614e55 100644
--- session/session_converter.h
+++ session/session_converter.h
@@ -395,7 +395,7 @@ class SessionConverter : public SessionConverterInterface {
   std::vector<int> selected_candidate_indices_;
 
   // Revision number of client context with which the converter determines when
-  // the history segments should be invalidated. See the implemenation of
+  // the history segments should be invalidated. See the implementation of
   // OnStartComposition for details.
   int32 client_revision_;
 
diff --git session/session_converter_interface.h session/session_converter_interface.h
index 32068a1ce..ba5b7f671 100644
--- session/session_converter_interface.h
+++ session/session_converter_interface.h
@@ -192,9 +192,9 @@ class SessionConverterInterface {
 
   // Commit prefix of the preedit string represented by Composer.
   // The caller should delete characters from composer based on returned
-  // |commited_size|.
+  // |committed_size|.
   virtual void CommitHead(size_t count, const composer::Composer &composer,
-                          size_t *commited_size) = 0;
+                          size_t *committed_size) = 0;
 
   // Revert the last "Commit" operation
   virtual void Revert() = 0;
diff --git session/session_converter_stress_test.cc session/session_converter_stress_test.cc
index cf112d022..36a4a2f7c 100644
--- session/session_converter_stress_test.cc
+++ session/session_converter_stress_test.cc
@@ -31,7 +31,6 @@
 #include <string>
 
 #include "base/clock.h"
-#include "base/flags.h"
 #include "base/port.h"
 #include "base/system_util.h"
 #include "base/util.h"
@@ -45,13 +44,14 @@
 #include "session/session_converter.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(bool, test_deterministic, true,
+ABSL_FLAG(bool, test_deterministic, true,
           "if true, srand() is initialized by \"test_srand_seed\"."
           "if false, srand() is initialized by current time "
           "and \"test_srand_seed\" is ignored");
 
-MOZC_FLAG(int32, test_srand_seed, 0,
+ABSL_FLAG(int32, test_srand_seed, 0,
           "seed number for srand(). "
           "used only when \"test_deterministic\" is true");
 
@@ -64,16 +64,16 @@ namespace session {
 class SessionConverterStressTest : public ::testing::Test {
  public:
   SessionConverterStressTest() {
-    if (!mozc::GetFlag(FLAGS_test_deterministic)) {
-      mozc::SetFlag(&FLAGS_test_srand_seed,
+    if (!absl::GetFlag(FLAGS_test_deterministic)) {
+      absl::SetFlag(&FLAGS_test_srand_seed,
                     static_cast<int32>(Clock::GetTime()));
     }
     Util::SetRandomSeed(
-        static_cast<uint32>(mozc::GetFlag(FLAGS_test_srand_seed)));
+        static_cast<uint32>(absl::GetFlag(FLAGS_test_srand_seed)));
   }
 
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     config::Config config;
     config::ConfigHandler::GetDefaultConfig(&config);
     config::ConfigHandler::SetConfig(config);
diff --git session/session_converter_test.cc session/session_converter_test.cc
index 8133d3dd1..d5c22add4 100644
--- session/session_converter_test.cc
+++ session/session_converter_test.cc
@@ -40,7 +40,6 @@
 #include <string>
 #include <vector>
 
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/system_util.h"
 #include "base/util.h"
@@ -62,6 +61,7 @@
 #include "transliteration/transliteration.h"
 #include "usage_stats/usage_stats.h"
 #include "usage_stats/usage_stats_testing_util.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 namespace mozc {
@@ -86,7 +86,7 @@ class SessionConverterTest : public ::testing::Test {
 
   void SetUp() override {
     convertermock_ = absl::make_unique<ConverterMock>();
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     mozc::usage_stats::UsageStats::ClearAllStatsForTest();
 
     config_ = absl::make_unique<Config>();
@@ -352,13 +352,13 @@ class SessionConverterTest : public ::testing::Test {
   }
 
   static void SetCommandCandidate(Segments *segments, int segment_index,
-                                  int canidate_index,
+                                  int candidate_index,
                                   Segment::Candidate::Command command) {
     segments->mutable_conversion_segment(segment_index)
-        ->mutable_candidate(canidate_index)
+        ->mutable_candidate(candidate_index)
         ->attributes |= Segment::Candidate::COMMAND_CANDIDATE;
     segments->mutable_conversion_segment(segment_index)
-        ->mutable_candidate(canidate_index)
+        ->mutable_candidate(candidate_index)
         ->command = command;
   }
 
diff --git session/session_handler.cc session/session_handler.cc
index 176e75283..9132ed5eb 100644
--- session/session_handler.cc
+++ session/session_handler.cc
@@ -38,9 +38,9 @@
 #include <vector>
 
 #include "base/clock.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/port.h"
+#include "absl/flags/flag.h"
 #ifndef MOZC_DISABLE_SESSION_WATCHDOG
 #include "base/process.h"
 #endif  // MOZC_DISABLE_SESSION_WATCHDOG
@@ -66,31 +66,31 @@
 
 using mozc::usage_stats::UsageStats;
 
-MOZC_FLAG(int32, timeout, -1,
+ABSL_FLAG(int32, timeout, -1,
           "server timeout. "
           "if sessions get empty for \"timeout\", "
           "shutdown message is automatically emitted");
 
-MOZC_FLAG(int32, max_session_size, 64,
+ABSL_FLAG(int32, max_session_size, 64,
           "maximum sessions size. "
           "if size of sessions reaches to \"max_session_size\", "
           "oldest session is removed");
 
-MOZC_FLAG(int32, create_session_min_interval, 0,
+ABSL_FLAG(int32, create_session_min_interval, 0,
           "minimum interval (sec) for create session");
 
-MOZC_FLAG(int32, watch_dog_interval, 180, "watch dog timer intaval (sec)");
+ABSL_FLAG(int32, watch_dog_interval, 180, "watch dog timer intaval (sec)");
 
-MOZC_FLAG(int32, last_command_timeout, 3600,
+ABSL_FLAG(int32, last_command_timeout, 3600,
           "remove session if it is not accessed for "
           "\"last_command_timeout\" sec");
 
-MOZC_FLAG(int32, last_create_session_timeout, 300,
+ABSL_FLAG(int32, last_create_session_timeout, 300,
           "remove session if it is not accessed for "
           "\"last_create_session_timeout\" sec "
           "after create session command");
 
-MOZC_FLAG(bool, restricted, false, "Launch server with restricted setting");
+ABSL_FLAG(bool, restricted, false, "Launch server with restricted setting");
 
 namespace mozc {
 
@@ -147,30 +147,30 @@ void SessionHandler::Init(
   request_ = absl::make_unique<commands::Request>();
   config_ = absl::make_unique<config::Config>();
 
-  if (mozc::GetFlag(FLAGS_restricted)) {
+  if (absl::GetFlag(FLAGS_restricted)) {
     VLOG(1) << "Server starts with restricted mode";
     // --restricted is almost always specified when mozc_client is inside Job.
     // The typical case is Startup processes on Vista.
     // On Vista, StartUp processes are in Job for 60 seconds. In order
     // to launch new mozc_server inside sandbox, we set the timeout
     // to be 60sec. Client application hopefully re-launch mozc_server.
-    mozc::SetFlag(&FLAGS_timeout, 60);
-    mozc::SetFlag(&FLAGS_max_session_size, 8);
-    mozc::SetFlag(&FLAGS_watch_dog_interval, 15);
-    mozc::SetFlag(&FLAGS_last_create_session_timeout, 60);
-    mozc::SetFlag(&FLAGS_last_command_timeout, 60);
+    absl::SetFlag(&FLAGS_timeout, 60);
+    absl::SetFlag(&FLAGS_max_session_size, 8);
+    absl::SetFlag(&FLAGS_watch_dog_interval, 15);
+    absl::SetFlag(&FLAGS_last_create_session_timeout, 60);
+    absl::SetFlag(&FLAGS_last_command_timeout, 60);
   }
 
 #ifndef MOZC_DISABLE_SESSION_WATCHDOG
   session_watch_dog_ = absl::make_unique<SessionWatchDog>(
-      mozc::GetFlag(FLAGS_watch_dog_interval));
+      absl::GetFlag(FLAGS_watch_dog_interval));
 #endif  // MOZC_DISABLE_SESSION_WATCHDOG
 
   config::ConfigHandler::GetConfig(config_.get());
 
   // allow [2..128] sessions
   max_session_size_ =
-      std::max(2, std::min(mozc::GetFlag(FLAGS_max_session_size), 128));
+      std::max(2, std::min(absl::GetFlag(FLAGS_max_session_size), 128));
   session_map_ = absl::make_unique<SessionMap>(max_session_size_);
 
   if (!engine_) {
@@ -493,7 +493,7 @@ bool SessionHandler::CreateSession(commands::Command *command) {
   // prevent DOS attack
   // don't allow CreateSession in very short period.
   const int create_session_minimum_interval =
-      std::max(0, std::min(mozc::GetFlag(FLAGS_create_session_min_interval),
+      std::max(0, std::min(absl::GetFlag(FLAGS_create_session_min_interval),
                            10));
 
   uint64 current_time = Clock::GetTime();
@@ -610,13 +610,13 @@ bool SessionHandler::Cleanup(commands::Command *command) {
   // allow [1..600] sec. default: 300
   const uint64 create_session_timeout =
       suspend_time +
-      std::max(1, std::min(mozc::GetFlag(FLAGS_last_create_session_timeout),
+      std::max(1, std::min(absl::GetFlag(FLAGS_last_create_session_timeout),
                            600));
 
   // allow [10..7200] sec. default 3600
   const uint64 last_command_timeout =
       suspend_time +
-      std::max(10, std::min(mozc::GetFlag(FLAGS_last_command_timeout), 7200));
+      std::max(10, std::min(absl::GetFlag(FLAGS_last_command_timeout), 7200));
 
   std::vector<SessionID> remove_ids;
   for (SessionElement *element =
@@ -649,9 +649,9 @@ bool SessionHandler::Cleanup(commands::Command *command) {
   engine_->GetUserDataManager()->Sync();
 
   // timeout is enabled.
-  if (mozc::GetFlag(FLAGS_timeout) > 0 && last_session_empty_time_ != 0 &&
+  if (absl::GetFlag(FLAGS_timeout) > 0 && last_session_empty_time_ != 0 &&
       (current_time - last_session_empty_time_) >=
-          suspend_time + mozc::GetFlag(FLAGS_timeout)) {
+          suspend_time + absl::GetFlag(FLAGS_timeout)) {
     Shutdown(command);
   }
 
diff --git session/session_handler.h session/session_handler.h
index 5f6d38912..8351e4e4c 100644
--- session/session_handler.h
+++ session/session_handler.h
@@ -83,7 +83,7 @@ class SessionHandler : public SessionHandlerInterface {
   // Starts watch dog timer to cleanup sessions.
   bool StartWatchDog() override;
 
-  // NewSession returns new Sessoin.
+  // NewSession returns new Session.
   // Client needs to delete it properly
   session::SessionInterface *NewSession();
 
diff --git session/session_handler_main.cc session/session_handler_main.cc
index acd9e34cf..a2cc71536 100644
--- session/session_handler_main.cc
+++ session/session_handler_main.cc
@@ -56,7 +56,6 @@ SHOW_LOG_BY_VALUE       ございました
 #include <string>
 
 #include "base/file_stream.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/status.h"
 #include "base/system_util.h"
@@ -66,12 +65,14 @@ SHOW_LOG_BY_VALUE       ございました
 #include "engine/engine.h"
 #include "protocol/commands.pb.h"
 #include "session/session_handler_tool.h"
+#include "absl/flags/flag.h"
 #include "absl/strings/str_split.h"
 
-MOZC_FLAG(string, input, "", "Input file");
-MOZC_FLAG(string, profile, "", "User profile directory");
-MOZC_FLAG(string, engine, "", "Conversion engine: 'mobile' or 'desktop'");
-MOZC_FLAG(string, dictionary, "", "Dictionary: 'google', 'android' or 'oss'");
+ABSL_FLAG(std::string, input, "", "Input file");
+ABSL_FLAG(std::string, profile, "", "User profile directory");
+ABSL_FLAG(std::string, engine, "", "Conversion engine: 'mobile' or 'desktop'");
+ABSL_FLAG(std::string, dictionary, "",
+          "Dictionary: 'google', 'android' or 'oss'");
 
 namespace mozc {
 void Show(const commands::Output &output) {
@@ -175,11 +176,11 @@ mozc::StatusOr<std::unique_ptr<Engine>> CreateEngine(
 
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
-  if (!mozc::GetFlag(FLAGS_profile).empty()) {
-    mozc::SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_profile));
+  if (!absl::GetFlag(FLAGS_profile).empty()) {
+    mozc::SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_profile));
   }
-  auto engine = mozc::CreateEngine(mozc::GetFlag(FLAGS_engine),
-                                   mozc::GetFlag(FLAGS_dictionary));
+  auto engine = mozc::CreateEngine(absl::GetFlag(FLAGS_engine),
+                                   absl::GetFlag(FLAGS_dictionary));
   if (!engine.ok()) {
     std::cout << "engine init error" << std::endl;
     return 1;
@@ -187,8 +188,8 @@ int main(int argc, char **argv) {
   mozc::session::SessionHandlerInterpreter handler(*std::move(engine));
 
   std::string line;
-  if (!mozc::GetFlag(FLAGS_input).empty()) {
-    mozc::InputFileStream input(mozc::GetFlag(FLAGS_input).c_str());
+  if (!absl::GetFlag(FLAGS_input).empty()) {
+    mozc::InputFileStream input(absl::GetFlag(FLAGS_input).c_str());
     while (std::getline(input, line)) {
       mozc::ParseLine(handler, line);
     }
diff --git session/session_handler_stress_test.cc session/session_handler_stress_test.cc
index f54e42016..22cf72891 100644
--- session/session_handler_stress_test.cc
+++ session/session_handler_stress_test.cc
@@ -33,7 +33,6 @@
 #include <vector>
 
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/port.h"
 #include "engine/engine_factory.h"
 #include "protocol/commands.pb.h"
@@ -42,6 +41,7 @@
 #include "session/session_handler_tool.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace {
 uint32 GenerateRandomSeed() {
@@ -52,7 +52,7 @@ uint32 GenerateRandomSeed() {
 }  // namespace
 
 // There is no DEFINE_uint32.
-MOZC_FLAG(uint64, random_seed, GenerateRandomSeed(),
+ABSL_FLAG(uint64, random_seed, GenerateRandomSeed(),
           "Random seed value. "
           "This value will be interpreted as uint32.");
 
@@ -71,7 +71,7 @@ TEST(SessionHandlerStressTest, BasicStressTest) {
   ASSERT_TRUE(client.CreateSession());
 
   const uint32 random_seed =
-      static_cast<uint32>(mozc::GetFlag(FLAGS_random_seed));
+      static_cast<uint32>(absl::GetFlag(FLAGS_random_seed));
   LOG(INFO) << "Random seed: " << random_seed;
   session::RandomKeyEventsGenerator::InitSeed(random_seed);
   while (keyevents_size < kMaxEventSize) {
diff --git session/session_handler_test.cc session/session_handler_test.cc
index 281ef0e90..92abaa457 100644
--- session/session_handler_test.cc
+++ session/session_handler_test.cc
@@ -36,7 +36,6 @@
 #include <vector>
 
 #include "base/clock_mock.h"
-#include "base/flags.h"
 #include "base/port.h"
 #include "base/util.h"
 #include "config/config_handler.h"
@@ -53,12 +52,14 @@
 #include "testing/base/public/gunit.h"
 #include "usage_stats/usage_stats.h"
 #include "usage_stats/usage_stats_testing_util.h"
+#include "absl/flags/declare.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
-MOZC_DECLARE_FLAG(int32, max_session_size);
-MOZC_DECLARE_FLAG(int32, create_session_min_interval);
-MOZC_DECLARE_FLAG(int32, last_command_timeout);
-MOZC_DECLARE_FLAG(int32, last_create_session_timeout);
+ABSL_DECLARE_FLAG(int32, max_session_size);
+ABSL_DECLARE_FLAG(int32, create_session_min_interval);
+ABSL_DECLARE_FLAG(int32, last_command_timeout);
+ABSL_DECLARE_FLAG(int32, last_create_session_timeout);
 
 namespace mozc {
 
@@ -197,13 +198,13 @@ class SessionHandlerTest : public SessionHandlerTestBase {
 TEST_F(SessionHandlerTest, MaxSessionSizeTest) {
   uint32 expected_session_created_num = 0;
   const int32 interval_time = 10;  // 10 sec
-  mozc::SetFlag(&FLAGS_create_session_min_interval, interval_time);
+  absl::SetFlag(&FLAGS_create_session_min_interval, interval_time);
   ClockMock clock(1000, 0);
   Clock::SetClockForUnitTest(&clock);
 
   // The oldest item is removed
   const size_t session_size = 3;
-  mozc::SetFlag(&FLAGS_max_session_size, static_cast<int32>(session_size));
+  absl::SetFlag(&FLAGS_max_session_size, static_cast<int32>(session_size));
   {
     SessionHandler handler(CreateMockDataEngine());
 
@@ -227,7 +228,7 @@ TEST_F(SessionHandlerTest, MaxSessionSizeTest) {
     }
   }
 
-  mozc::SetFlag(&FLAGS_max_session_size, static_cast<int32>(session_size));
+  absl::SetFlag(&FLAGS_max_session_size, static_cast<int32>(session_size));
   {
     SessionHandler handler(CreateMockDataEngine());
 
@@ -265,7 +266,7 @@ TEST_F(SessionHandlerTest, MaxSessionSizeTest) {
 
 TEST_F(SessionHandlerTest, CreateSessionMinInterval) {
   const int32 interval_time = 10;  // 10 sec
-  mozc::SetFlag(&FLAGS_create_session_min_interval, interval_time);
+  absl::SetFlag(&FLAGS_create_session_min_interval, interval_time);
   ClockMock clock(1000, 0);
   Clock::SetClockForUnitTest(&clock);
 
@@ -286,7 +287,7 @@ TEST_F(SessionHandlerTest, CreateSessionMinInterval) {
 
 TEST_F(SessionHandlerTest, LastCreateSessionTimeout) {
   const int32 timeout = 10;  // 10 sec
-  mozc::SetFlag(&FLAGS_last_create_session_timeout, timeout);
+  absl::SetFlag(&FLAGS_last_create_session_timeout, timeout);
   ClockMock clock(1000, 0);
   Clock::SetClockForUnitTest(&clock);
 
@@ -306,7 +307,7 @@ TEST_F(SessionHandlerTest, LastCreateSessionTimeout) {
 
 TEST_F(SessionHandlerTest, LastCommandTimeout) {
   const int32 timeout = 10;  // 10 sec
-  mozc::SetFlag(&FLAGS_last_command_timeout, timeout);
+  absl::SetFlag(&FLAGS_last_command_timeout, timeout);
   ClockMock clock(1000, 0);
   Clock::SetClockForUnitTest(&clock);
 
diff --git session/session_handler_test_util.cc session/session_handler_test_util.cc
index ce3a30596..dd94c41d0 100644
--- session/session_handler_test_util.cc
+++ session/session_handler_test_util.cc
@@ -33,7 +33,6 @@
 
 #include "base/config_file_stream.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/system_util.h"
 #include "config/character_form_manager.h"
@@ -47,13 +46,15 @@
 #include "session/session_usage_observer.h"
 #include "storage/registry.h"
 #include "testing/base/public/googletest.h"
+#include "absl/flags/declare.h"
+#include "absl/flags/flag.h"
 
-MOZC_DECLARE_FLAG(int32, max_session_size);
-MOZC_DECLARE_FLAG(int32, create_session_min_interval);
-MOZC_DECLARE_FLAG(int32, watch_dog_interval);
-MOZC_DECLARE_FLAG(int32, last_command_timeout);
-MOZC_DECLARE_FLAG(int32, last_create_session_timeout);
-MOZC_DECLARE_FLAG(bool, restricted);
+ABSL_DECLARE_FLAG(int32, max_session_size);
+ABSL_DECLARE_FLAG(int32, create_session_min_interval);
+ABSL_DECLARE_FLAG(int32, watch_dog_interval);
+ABSL_DECLARE_FLAG(int32, last_command_timeout);
+ABSL_DECLARE_FLAG(int32, last_create_session_timeout);
+ABSL_DECLARE_FLAG(bool, restricted);
 
 namespace mozc {
 namespace session {
@@ -110,18 +111,18 @@ SessionHandlerTestBase::SessionHandlerTestBase() {}
 SessionHandlerTestBase::~SessionHandlerTestBase() {}
 
 void SessionHandlerTestBase::SetUp() {
-  flags_max_session_size_backup_ = mozc::GetFlag(FLAGS_max_session_size);
+  flags_max_session_size_backup_ = absl::GetFlag(FLAGS_max_session_size);
   flags_create_session_min_interval_backup_ =
-      mozc::GetFlag(FLAGS_create_session_min_interval);
-  flags_watch_dog_interval_backup_ = mozc::GetFlag(FLAGS_watch_dog_interval);
+      absl::GetFlag(FLAGS_create_session_min_interval);
+  flags_watch_dog_interval_backup_ = absl::GetFlag(FLAGS_watch_dog_interval);
   flags_last_command_timeout_backup_ =
-      mozc::GetFlag(FLAGS_last_command_timeout);
+      absl::GetFlag(FLAGS_last_command_timeout);
   flags_last_create_session_timeout_backup_ =
-      mozc::GetFlag(FLAGS_last_create_session_timeout);
-  flags_restricted_backup_ = mozc::GetFlag(FLAGS_restricted);
+      absl::GetFlag(FLAGS_last_create_session_timeout);
+  flags_restricted_backup_ = absl::GetFlag(FLAGS_restricted);
 
   user_profile_directory_backup_ = SystemUtil::GetUserProfileDirectory();
-  SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+  SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   ConfigHandler::GetConfig(&config_backup_);
   ClearState();
 }
@@ -131,15 +132,15 @@ void SessionHandlerTestBase::TearDown() {
   ConfigHandler::SetConfig(config_backup_);
   SystemUtil::SetUserProfileDirectory(user_profile_directory_backup_);
 
-  mozc::SetFlag(&FLAGS_max_session_size, flags_max_session_size_backup_);
-  mozc::SetFlag(&FLAGS_create_session_min_interval,
+  absl::SetFlag(&FLAGS_max_session_size, flags_max_session_size_backup_);
+  absl::SetFlag(&FLAGS_create_session_min_interval,
                 flags_create_session_min_interval_backup_);
-  mozc::SetFlag(&FLAGS_watch_dog_interval, flags_watch_dog_interval_backup_);
-  mozc::SetFlag(&FLAGS_last_command_timeout,
+  absl::SetFlag(&FLAGS_watch_dog_interval, flags_watch_dog_interval_backup_);
+  absl::SetFlag(&FLAGS_last_command_timeout,
                 flags_last_command_timeout_backup_);
-  mozc::SetFlag(&FLAGS_last_create_session_timeout,
+  absl::SetFlag(&FLAGS_last_create_session_timeout,
                 flags_last_create_session_timeout_backup_);
-  mozc::SetFlag(&FLAGS_restricted, flags_restricted_backup_);
+  absl::SetFlag(&FLAGS_restricted, flags_restricted_backup_);
 }
 
 void SessionHandlerTestBase::ClearState() {
diff --git session/session_regression_test.cc session/session_regression_test.cc
index 2d64e9010..2b806fab3 100644
--- session/session_regression_test.cc
+++ session/session_regression_test.cc
@@ -35,7 +35,6 @@
 #include <utility>
 
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/port.h"
 #include "base/system_util.h"
@@ -58,9 +57,11 @@
 #include "session/session_handler.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/declare.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
-MOZC_DECLARE_FLAG(bool, use_history_rewriter);
+ABSL_DECLARE_FLAG(bool, use_history_rewriter);
 
 namespace mozc {
 namespace {
@@ -91,10 +92,10 @@ void InitSessionToPrecomposition(session::Session *session) {
 class SessionRegressionTest : public ::testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
 
-    orig_use_history_rewriter_ = mozc::GetFlag(FLAGS_use_history_rewriter);
-    mozc::SetFlag(&FLAGS_use_history_rewriter, true);
+    orig_use_history_rewriter_ = absl::GetFlag(FLAGS_use_history_rewriter);
+    absl::SetFlag(&FLAGS_use_history_rewriter, true);
 
     // Note: engine must be created after setting all the flags, as it
     // internally depends on global flags, e.g., for creation of rewriters.
@@ -117,7 +118,7 @@ class SessionRegressionTest : public ::testing::Test {
     config::ConfigHandler::GetDefaultConfig(&config);
     config::ConfigHandler::SetConfig(config);
 
-    mozc::SetFlag(&FLAGS_use_history_rewriter, orig_use_history_rewriter_);
+    absl::SetFlag(&FLAGS_use_history_rewriter, orig_use_history_rewriter_);
   }
 
   bool SendKey(const std::string &key, commands::Command *command) {
@@ -215,7 +216,7 @@ TEST_F(SessionRegressionTest, ConvertToTransliterationWithMultipleSegments) {
 }
 
 TEST_F(SessionRegressionTest,
-       ExitTemporaryAlphanumModeAfterCommitingSugesstion) {
+       ExitTemporaryAlphanumModeAfterCommittingSugesstion) {
   // This is a regression test against http://b/2977131.
   {
     InitSessionToPrecomposition(session_.get());
@@ -247,7 +248,7 @@ TEST_F(SessionRegressionTest, HistoryLearning) {
   std::string candidate1;
   std::string candidate2;
 
-  {  // First session.  Second candidate is commited.
+  {  // First session.  Second candidate is committed.
     InsertCharacterChars("kanji", &command);
 
     command.Clear();
diff --git session/session_server_main.cc session/session_server_main.cc
index e9eae5b1c..4956d517d 100644
--- session/session_server_main.cc
+++ session/session_server_main.cc
@@ -30,10 +30,10 @@
 // Mocked Session Server runner used just for testing.
 #include <cstdio>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "protocol/commands.pb.h"
 #include "session/session_server.h"
+#include "absl/flags/flag.h"
 #include "absl/strings/str_format.h"
 
 static const int kMaxBufSize = 1024;
diff --git session/session_server_test.cc session/session_server_test.cc
index 3b1439113..7a64d543f 100644
--- session/session_server_test.cc
+++ session/session_server_test.cc
@@ -33,11 +33,11 @@
 #include <string>
 #include <vector>
 
-#include "base/flags.h"
 #include "base/scheduler.h"
 #include "base/system_util.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace {
@@ -68,7 +68,7 @@ class JobRecorder : public Scheduler::SchedulerInterface {
 class SessionServerTest : public testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
   }
 };
 
diff --git session/session_test.cc session/session_test.cc
index c7c1296bc..2c44228b5 100644
--- session/session_test.cc
+++ session/session_test.cc
@@ -3212,7 +3212,7 @@ TEST_F(SessionTest, SpaceOnAlphanumeric) {
 
   {
     request.set_space_on_alphanumeric(
-        commands::Request::SPACE_OR_CONVERT_COMMITING_COMPOSITION);
+        commands::Request::SPACE_OR_CONVERT_COMMITTING_COMPOSITION);
 
     Session session(engine_.get());
     InitSessionToPrecomposition(&session, request);
@@ -3687,7 +3687,7 @@ TEST_F(SessionTest, InsertCharacterWithShiftKey) {
   }
 }
 
-TEST_F(SessionTest, ExitTemporaryAlphanumModeAfterCommitingSugesstion) {
+TEST_F(SessionTest, ExitTemporaryAlphanumModeAfterCommittingSugesstion) {
   // This is a unittest against http://b/2977131.
   {
     std::unique_ptr<Session> session(new Session(engine_.get()));
@@ -8638,7 +8638,7 @@ TEST_F(SessionTest, CancelInPasswordMode_Issue5955618) {
     InitSessionToConversionWithAiueo(&session);
     SwitchInputFieldType(commands::Context::PASSWORD, &session);
 
-    // Actualy this works well because Cancel command in conversion mode
+    // Actually this works well because Cancel command in conversion mode
     // is mapped into ConvertCancel not EditCancel.
     commands::Command command;
     EXPECT_TRUE(TestSendKey("ESC", &session, &command));
@@ -8664,7 +8664,7 @@ TEST_F(SessionTest, CancelInPasswordMode_Issue5955618) {
     SetupMockForReverseConversion("[MO]", "MO");
     EXPECT_TRUE(session.SendCommand(&command));
 
-    // Actualy this works well because Cancel command in conversion mode
+    // Actually this works well because Cancel command in conversion mode
     // is mapped into ConvertCancel not EditCancel.
     EXPECT_TRUE(TestSendKey("ESC", &session, &command));
     EXPECT_TRUE(command.output().consumed());
@@ -8890,7 +8890,7 @@ TEST_F(SessionTest, SuppressSuggestion) {
   SendKey("d", &session, &command);
   EXPECT_TRUE(command.output().has_candidates());
 
-  // With an invalid identifer.  It should be the same with the
+  // With an invalid identifier.  It should be the same with the
   // default behavior.
   SetSendKeyCommand("i", &command);
   command.mutable_input()->mutable_context()->add_experimental_features(
diff --git session/session_usage_observer.cc session/session_usage_observer.cc
index e78135318..42ac1f3c3 100644
--- session/session_usage_observer.cc
+++ session/session_usage_observer.cc
@@ -101,13 +101,13 @@ bool IsSessionIndependentCommand(commands::Input::CommandType type) {
 }  // namespace
 
 SessionUsageObserver::SessionUsageObserver() {
-  // Explicitly calls Sync() to delete usage stats existing data inlcuding
+  // Explicitly calls Sync() to delete usage stats existing data including
   // metadata for migration.
   UsageStats::Sync();
 }
 
 SessionUsageObserver::~SessionUsageObserver() {
-  // Explicitly calls Sync() to delete usage stats existing data inlcuding
+  // Explicitly calls Sync() to delete usage stats existing data including
   // metadata for migration.
   UsageStats::Sync();
 }
diff --git session/session_usage_observer.h session/session_usage_observer.h
index 0667e77d1..ba754fa1e 100644
--- session/session_usage_observer.h
+++ session/session_usage_observer.h
@@ -103,7 +103,7 @@ class SessionUsageObserver : public SessionObserverInterface {
 
   // last_touchevents_ is used to keep the touch_events of last SEND_KEY
   // message.
-  // When the subsequent command will be recieved, if the command is BACKSPACE
+  // When the subsequent command will be received, if the command is BACKSPACE
   // last_touchevents_ will be aggregated to miss_touch_event_stat_cache_,
   // if the command is not BACKSPACE last_touchevents_ will be aggregated to
   // touch_event_stat_cache_.
diff --git session/session_usage_observer_test.cc session/session_usage_observer_test.cc
index 337a910f7..1b858e880 100644
--- session/session_usage_observer_test.cc
+++ session/session_usage_observer_test.cc
@@ -34,7 +34,6 @@
 
 #include "base/clock.h"
 #include "base/clock_mock.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/scheduler.h"
 #include "base/scheduler_stub.h"
@@ -48,6 +47,7 @@
 #include "usage_stats/usage_stats.h"
 #include "usage_stats/usage_stats.pb.h"
 #include "usage_stats/usage_stats_testing_util.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 using mozc::usage_stats::Stats;
@@ -59,7 +59,7 @@ namespace session {
 class SessionUsageObserverTest : public testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     UsageStats::ClearAllStatsForTest();
 
     Clock::SetClockForUnitTest(nullptr);
diff --git storage/BUILD storage/BUILD
index 5d55b0a8e..93fa640f1 100644
--- storage/BUILD
+++ storage/BUILD
@@ -109,11 +109,11 @@ cc_test_mozc(
         "//base:clock_mock",
         "//base:file_stream",
         "//base:file_util",
-        "//base:flags",
         "//base:logging",
         "//base:port",
         "//base:util",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -161,9 +161,9 @@ cc_test_mozc(
         ":tiny_storage",
         "//base",
         "//base:file_util",
-        "//base:flags",
         "//base:port",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings:str_format",
     ],
 )
@@ -216,9 +216,9 @@ cc_test_mozc(
     deps = [
         ":registry",
         "//base",
-        "//base:flags",
         "//base:system_util",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -246,10 +246,10 @@ cc_test_mozc(
         ":encrypted_string_storage",
         "//base:file_stream",
         "//base:file_util",
-        "//base:flags",
         "//base:logging",
         "//base:system_util",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/memory",
     ],
 )
diff --git storage/encrypted_string_storage_test.cc storage/encrypted_string_storage_test.cc
index 0ddaeb456..c4e0b4d8e 100644
--- storage/encrypted_string_storage_test.cc
+++ storage/encrypted_string_storage_test.cc
@@ -34,11 +34,11 @@
 
 #include "base/file_stream.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/system_util.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 #include "absl/memory/memory.h"
 
 namespace mozc {
@@ -82,7 +82,7 @@ typedef EncryptedStringStorage TestEncryptedStringStorage;
 class EncryptedStringStorageTest : public testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     filename_ = FileUtil::JoinPath(SystemUtil::GetUserProfileDirectory(),
                                    "encrypted_string_storage_for_test.db");
 
@@ -122,7 +122,7 @@ TEST_F(EncryptedStringStorageTest, Encrypt) {
   ASSERT_TRUE(ifs.eof());
   const std::string result(buf, read_size);
 
-  // Saved stirng is longer than original string since it has some data
+  // Saved string is longer than original string since it has some data
   // used for encryption.
   EXPECT_LT(original_data.size(), result.size());
   EXPECT_TRUE(result.find(original_data) == std::string::npos);
diff --git storage/existence_filter_main.cc storage/existence_filter_main.cc
index e2731b4a0..cfdcda837 100644
--- storage/existence_filter_main.cc
+++ storage/existence_filter_main.cc
@@ -29,12 +29,12 @@
 
 #include <string>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/port.h"
 #include "base/util.h"
 #include "storage/existence_filter.h"
+#include "absl/flags/flag.h"
 
 using mozc::storage::ExistenceFilter;
 
diff --git storage/lru_cache_main.cc storage/lru_cache_main.cc
index 61372ec23..e8a8e33e6 100644
--- storage/lru_cache_main.cc
+++ storage/lru_cache_main.cc
@@ -30,10 +30,10 @@
 #include <iostream>  // NOLINT
 #include <string>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/util.h"
 #include "storage/lru_cache.h"
+#include "absl/flags/flag.h"
 
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
diff --git storage/lru_storage.h storage/lru_storage.h
index 03e31af5c..4a85c4502 100644
--- storage/lru_storage.h
+++ storage/lru_storage.h
@@ -54,7 +54,7 @@ class LRUStorage {
   bool Open(const char *filename);
   void Close();
 
-  // Try to open exisiting database
+  // Try to open existing database
   // If the file is broken or cannot open, tries to recreate
   // new file
   bool OpenOrCreate(const char *filename, size_t new_value_size,
diff --git storage/lru_storage_main.cc storage/lru_storage_main.cc
index 7dd758ab0..92d5b9276 100644
--- storage/lru_storage_main.cc
+++ storage/lru_storage_main.cc
@@ -29,29 +29,29 @@
 
 #include <string>
 
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/port.h"
 #include "base/util.h"
 #include "storage/lru_storage.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(bool, create_db, false, "initialize database");
-MOZC_FLAG(string, file, "test.db", "");
-MOZC_FLAG(int32, size, 10, "size");
+ABSL_FLAG(bool, create_db, false, "initialize database");
+ABSL_FLAG(std::string, file, "test.db", "");
+ABSL_FLAG(int32, size, 10, "size");
 
 using mozc::storage::LRUStorage;
 
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
 
-  if (mozc::GetFlag(FLAGS_create_db)) {
+  if (absl::GetFlag(FLAGS_create_db)) {
     CHECK(LRUStorage::CreateStorageFile(FLAGS_file.c_str(),
                                         static_cast<uint32>(4),
-                                        mozc::GetFlag(FLAGS_size), 0xff02));
+                                        absl::GetFlag(FLAGS_size), 0xff02));
   }
 
   LRUStorage s;
-  CHECK(s.Open(mozc::GetFlag(FLAGS_file).c_str()));
+  CHECK(s.Open(absl::GetFlag(FLAGS_file).c_str()));
 
   LOG(INFO) << "size=" << s.size();
   LOG(INFO) << "used_size=" << s.used_size();
diff --git storage/lru_storage_test.cc storage/lru_storage_test.cc
index 90f3c189c..37dfd2f1d 100644
--- storage/lru_storage_test.cc
+++ storage/lru_storage_test.cc
@@ -38,13 +38,13 @@
 #include "base/clock_mock.h"
 #include "base/file_stream.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/port.h"
 #include "base/util.h"
 #include "storage/lru_cache.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace storage {
@@ -137,7 +137,7 @@ class LRUStorageTest : public ::testing::Test {
 
   static std::string GetTemporaryFilePath() {
     // This name should be unique to each test.
-    return FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir),
+    return FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir),
                               "LRUStorageTest_test.db");
   }
 
@@ -245,7 +245,7 @@ TEST_F(LRUStorageTest, Merge) {
 
   {
     // Need to mock clock because old entries are removed on Open.  The maximum
-    // timestmap set below is 50, so set the current time to 100.
+    // timestamp set below is 50, so set the current time to 100.
     ScopedClockMock clock(100, 0);
 
     LRUStorage::CreateStorageFile(file1.c_str(), 4, 8, kSeed);
@@ -288,7 +288,7 @@ TEST_F(LRUStorageTest, Merge) {
   // same FP
   {
     // Need to mock clock because old entries are removed on Open.  The maximum
-    // timestmap set below is 50, so set the current time to 100.
+    // timestamp set below is 50, so set the current time to 100.
     ScopedClockMock clock(100, 0);
 
     LRUStorage::CreateStorageFile(file1.c_str(), 4, 8, kSeed);
diff --git storage/registry_test.cc storage/registry_test.cc
index 4e14d9616..a4c3d11ca 100644
--- storage/registry_test.cc
+++ storage/registry_test.cc
@@ -31,16 +31,16 @@
 
 #include <string>
 
-#include "base/flags.h"
 #include "base/system_util.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace storage {
 
 TEST(RegistryTest, TinyStorageTest) {
-  SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+  SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
 
   {
     uint64 value = 20;
diff --git storage/storage_interface.h storage/storage_interface.h
index c691a733d..3b6524adf 100644
--- storage/storage_interface.h
+++ storage/storage_interface.h
@@ -56,15 +56,15 @@ class StorageInterface {
 
   // Looks up key and returns the value.
   // If key is not found, returns false.
-  // It is not guranteed that the data is synced to the disk.
+  // It is not guaranteed that the data is synced to the disk.
   virtual bool Lookup(const std::string &key, std::string *value) const = 0;
 
   // Inserts key and value.
-  // It is not guranteed that the data is synced to the disk.
+  // It is not guaranteed that the data is synced to the disk.
   virtual bool Insert(const std::string &key, const std::string &value) = 0;
 
   // Erases the key-value pair specified by |key|.
-  // It is not guranteed that the data is synced to the disk
+  // It is not guaranteed that the data is synced to the disk
   virtual bool Erase(const std::string &key) = 0;
 
   // clears internal keys and values
diff --git storage/tiny_storage.h storage/tiny_storage.h
index 6bbcdb8c0..3a9c1c7b7 100644
--- storage/tiny_storage.h
+++ storage/tiny_storage.h
@@ -42,7 +42,7 @@ namespace storage {
 // We will replace it with faster and more robust implementation.
 class TinyStorage {
  public:
-  // Returns an implementatoin of StorageInterface.
+  // Returns an implementation of StorageInterface.
   // Caller must take ownership of the returned object.
   // Returns NULL if fails.
   static StorageInterface *New();
diff --git storage/tiny_storage_test.cc storage/tiny_storage_test.cc
index e8f5a3a32..755ecca00 100644
--- storage/tiny_storage_test.cc
+++ storage/tiny_storage_test.cc
@@ -37,11 +37,11 @@
 #include <vector>
 
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/port.h"
 #include "storage/storage_interface.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 #include "absl/strings/str_format.h"
 
 namespace mozc {
@@ -80,7 +80,7 @@ class TinyStorageTest : public testing::Test {
 
   static std::string GetTemporaryFilePath() {
     // This name should be unique to each test.
-    return FileUtil::JoinPath(mozc::GetFlag(FLAGS_test_tmpdir),
+    return FileUtil::JoinPath(absl::GetFlag(FLAGS_test_tmpdir),
                               "TinyStorageTest_test.db");
   }
 
diff --git testing/BUILD testing/BUILD
index b840b33c0..2aed40512 100644
--- testing/BUILD
+++ testing/BUILD
@@ -77,7 +77,7 @@ cc_library_mozc(
     deps = [
         ":gunit",
         "//base",
-        "//base:flags",
+        "@com_google_absl//absl/flags:flag",
     ] + select_mozc(
         client = [
             "//base:init_mozc",
@@ -154,7 +154,7 @@ cc_library_mozc(
             "//base",
             "//base:logging",
             "//base:file_util",
-            "//base:flags",
+            "@com_google_absl//absl/flags:flag",
             "//base:util",
         ],
         default = ["//testing/base/public:gunit_for_library_testonly"],
@@ -173,11 +173,11 @@ cc_library_mozc(
         ":googletest",
         "//base",
         "//base:file_util",
-        "//base:flags",
         "//base:logging",
         "//base:port",
         "//base:system_util",
         "//base:util",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings",
     ],
 )
diff --git testing/base/internal/googletest.cc testing/base/internal/googletest.cc
index a3610a2f4..e64ce2448 100644
--- testing/base/internal/googletest.cc
+++ testing/base/internal/googletest.cc
@@ -40,17 +40,18 @@
 #include <string>
 
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/util.h"
+#include "absl/flags/declare.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, test_srcdir, "",
+ABSL_FLAG(std::string, test_srcdir, "",
           "A directory that contains the input data files for a test.");
 
-MOZC_FLAG(string, test_tmpdir, "",
+ABSL_FLAG(std::string, test_tmpdir, "",
           "Directory for all temporary testing files.");
 
-MOZC_DECLARE_FLAG(string, program_invocation_name);
+ABSL_DECLARE_FLAG(string, program_invocation_name);
 
 namespace mozc {
 namespace {
@@ -95,7 +96,7 @@ string GetTestTmpdir() {
 // directory information. E.g like "/spam/eggs/foo_unittest".
 string GetProgramPath() {
   const string& program_invocation_name =
-      mozc::GetFlag(FLAGS_program_invocation_name);
+      absl::GetFlag(FLAGS_program_invocation_name);
   if (program_invocation_name.empty() || program_invocation_name[0] == '/') {
     return program_invocation_name;
   }
@@ -144,11 +145,11 @@ string GetTestTmpdir() {
 }  // namespace
 
 void InitTestFlags() {
-  if (mozc::GetFlag(FLAGS_test_srcdir).empty()) {
-    mozc::SetFlag(&FLAGS_test_srcdir, GetTestSrcdir());
+  if (absl::GetFlag(FLAGS_test_srcdir).empty()) {
+    absl::SetFlag(&FLAGS_test_srcdir, GetTestSrcdir());
   }
-  if (mozc::GetFlag(FLAGS_test_tmpdir).empty()) {
-    mozc::SetFlag(&FLAGS_test_tmpdir, GetTestTmpdir());
+  if (absl::GetFlag(FLAGS_test_tmpdir).empty()) {
+    absl::SetFlag(&FLAGS_test_tmpdir, GetTestTmpdir());
   }
 }
 
diff --git testing/base/internal/gtest_main.cc testing/base/internal/gtest_main.cc
index b6666ff0d..b753339b3 100644
--- testing/base/internal/gtest_main.cc
+++ testing/base/internal/gtest_main.cc
@@ -28,10 +28,10 @@
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
+#include "absl/flags/flag.h"
 
 int main(int argc, char **argv) {
   // TODO(yukawa, team): Implement b/2805528 so that you can specify any option
diff --git testing/base/public/googletest.h testing/base/public/googletest.h
index ed1fa238d..2fa5513aa 100644
--- testing/base/public/googletest.h
+++ testing/base/public/googletest.h
@@ -30,7 +30,8 @@
 #ifndef MOZC_TESTING_BASE_PUBLIC_GOOGLETEST_H_
 #define MOZC_TESTING_BASE_PUBLIC_GOOGLETEST_H_
 
-#include "base/flags.h"
+#include "absl/flags/declare.h"
+#include "absl/flags/flag.h"
 
 // gunit doesn't expose test_srcdir and test_tmpdir on mobile platforms like
 // Android.
@@ -38,13 +39,13 @@
 // --test_srcdir is the path to a directory that contains the input data files
 // for a test, so that each entry in the 'data' section of the BUILD rule for
 // this test specifies a path relative to FLAGS_test_srcdir.
-MOZC_DECLARE_FLAG(string, test_srcdir);
+ABSL_DECLARE_FLAG(std::string, test_srcdir);
 
 // --test_tmpdir is a temporary directory that you can write to from inside a
 // test.  Files you write will eventually be cleaned up but you can see them at
 // ~/local/tmp in the immediate aftermath of the test.  These files are
 // stored on local disk, not on the networked filer.
-MOZC_DECLARE_FLAG(string, test_tmpdir);
+ABSL_DECLARE_FLAG(std::string, test_tmpdir);
 
 namespace mozc {
 // Initialize FLAGS_test_srcdir and FLAGS_test_tmpdir.
diff --git testing/base/public/mozctest.cc testing/base/public/mozctest.cc
index 6e30fc48f..25f42c379 100644
--- testing/base/public/mozctest.cc
+++ testing/base/public/mozctest.cc
@@ -30,18 +30,18 @@
 #include "testing/base/public/mozctest.h"
 
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/system_util.h"
 #include "base/util.h"
 #include "testing/base/public/googletest.h"
+#include "absl/flags/flag.h"
 #include "absl/strings/string_view.h"
 
 namespace mozc {
 namespace testing {
 
 std::string GetSourcePath(const std::vector<absl::string_view> &components) {
-  const std::string test_srcdir = mozc::GetFlag(FLAGS_test_srcdir);
+  const std::string test_srcdir = absl::GetFlag(FLAGS_test_srcdir);
   std::vector<absl::string_view> abs_components = { test_srcdir };
 
   const char *workspace = std::getenv("TEST_WORKSPACE");
@@ -83,7 +83,7 @@ std::vector<std::string> GetSourceFilesInDirOrDie(
 
 ScopedTmpUserProfileDirectory::ScopedTmpUserProfileDirectory()
     : original_dir_(SystemUtil::GetUserProfileDirectory()) {
-  SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+  SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
 }
 
 ScopedTmpUserProfileDirectory::~ScopedTmpUserProfileDirectory() {
diff --git tools/build_defs/qt.bzl tools/build_defs/qt.bzl
index 0a1ee34e8..14e676b47 100644
--- tools/build_defs/qt.bzl
+++ tools/build_defs/qt.bzl
@@ -117,7 +117,7 @@ def macos_qt_application_mozc(name, bundle_name, deps):
         app_icons = ["//data/images/mac:product_icon.icns"],
         bundle_id = MACOS_BUNDLE_ID_PREFIX + ".Tool." + bundle_name,
         bundle_name = bundle_name,
-        infoplists = ["//gui:gen_mozc_tool_info_plist"],
+        infoplists = ["//gui:mozc_tool_info_plist"],
         minimum_os_version = MACOS_MIN_OS_VER,
         resources = ["//data/images/mac:candidate_window_logo.tiff"],
         visibility = ["//:__subpackages__"],
diff --git tools/cc_target_os/BUILD tools/cc_target_os/BUILD
index 6a6ac82d2..ee11dd19b 100644
--- tools/cc_target_os/BUILD
+++ tools/cc_target_os/BUILD
@@ -104,3 +104,10 @@ config_setting(
         "define": "TARGET=wasm",
     },
 )
+
+config_setting(
+    name = "windows",
+    values = {
+        "define": "TARGET=windows",
+    },
+)
diff --git unix/emacs/BUILD unix/emacs/BUILD
index f73fd970a..bc1224a48 100644
--- unix/emacs/BUILD
+++ unix/emacs/BUILD
@@ -48,7 +48,6 @@ cc_binary_mozc(
     deps = [
         ":mozc_emacs_helper_lib",
         "//base",
-        "//base:flags",
         "//base:init_mozc",
         "//base:logging",
         "//base:util",
@@ -57,6 +56,7 @@ cc_binary_mozc(
         "//config:config_handler",
         "//ipc",
         "//protocol:commands_proto",
+        "@com_google_absl//absl/flags:flag",
         "@com_google_absl//absl/strings:str_format",
     ],
 )
diff --git unix/emacs/mozc_emacs_helper.cc unix/emacs/mozc_emacs_helper.cc
index 562b23221..3416547da 100644
--- unix/emacs/mozc_emacs_helper.cc
+++ unix/emacs/mozc_emacs_helper.cc
@@ -30,7 +30,6 @@
 #include <cstdio>
 #include <iostream>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/util.h"
@@ -40,9 +39,10 @@
 #include "protocol/commands.pb.h"
 #include "unix/emacs/client_pool.h"
 #include "unix/emacs/mozc_emacs_helper_lib.h"
+#include "absl/flags/flag.h"
 #include "absl/strings/str_format.h"
 
-MOZC_FLAG(bool, suppress_stderr, false, "Discards all the output to stderr.");
+ABSL_FLAG(bool, suppress_stderr, false, "Discards all the output to stderr.");
 
 namespace {
 
@@ -125,7 +125,7 @@ void ProcessLoop() {
 
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
-  if (mozc::GetFlag(FLAGS_suppress_stderr)) {
+  if (absl::GetFlag(FLAGS_suppress_stderr)) {
 #ifdef OS_WIN
     const char path[] = "NUL";
 #else
diff --git unix/emacs/mozc_emacs_helper_lib.h unix/emacs/mozc_emacs_helper_lib.h
index 22ecffb08..775e6eb2d 100644
--- unix/emacs/mozc_emacs_helper_lib.h
+++ unix/emacs/mozc_emacs_helper_lib.h
@@ -110,7 +110,7 @@ void ErrorExit(const std::string &error, const std::string &message);
 // Removes unused usage information from output protocol buffers.
 // Usage data may contain line breaks, which have not been supported yet for IPC
 // in S-expression. Only single line S-expressions are supported so far.
-// This function retuns true if usage data is removed.
+// This function returns true if usage data is removed.
 bool RemoveUsageData(mozc::commands::Output *output);
 
 }  // namespace emacs
diff --git unix/ibus/BUILD unix/ibus/BUILD
index ea7d08346..62d6f84c3 100644
--- unix/ibus/BUILD
+++ unix/ibus/BUILD
@@ -229,8 +229,8 @@ cc_binary_mozc(
         ":ibus_mozc_lib",
         ":ibus_mozc_metadata",
         "//base",
-        "//base:flags",
         "//base:init_mozc",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
diff --git unix/ibus/key_translator_test.cc unix/ibus/key_translator_test.cc
index a39d51e57..0664abc0b 100644
--- unix/ibus/key_translator_test.cc
+++ unix/ibus/key_translator_test.cc
@@ -216,7 +216,7 @@ TEST_F(KeyTranslatorTest, TranslateSingleModifierMasks) {
   // keyboard are not assigned Shift-0 character. So that, we expect the client
   // send keycode='0'(\x30) with shift modifier, but currently only send
   // keycode='0'. There are few difficulties because the mapping of Shift-0 are
-  // controled xkb in X11, but the way to get the mapping is unclear.
+  // controlled xkb in X11, but the way to get the mapping is unclear.
 
   // ALT modifier
   // M-F1
@@ -507,7 +507,7 @@ TEST_F(KeyTranslatorTest, MultipleShiftKeysTest) {
   IsContained(commands::KeyEvent::SHIFT, out.modifier_keys());
 }
 
-TEST_F(KeyTranslatorTest, TranslateUnknow) {
+TEST_F(KeyTranslatorTest, TranslateUnknown) {
   commands::KeyEvent out;
   EXPECT_FALSE(translator_->Translate(IBUS_VoidSymbol, 0, 0,
                                       config::Config::ROMAN, true, &out));
diff --git unix/ibus/main.cc unix/ibus/main.cc
index b7852cbb4..6813d131a 100644
--- unix/ibus/main.cc
+++ unix/ibus/main.cc
@@ -27,20 +27,21 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+#include "unix/ibus/main.h"
+
 #include <cstddef>
 #include <cstdio>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/logging.h"
 #include "base/version.h"
 #include "unix/ibus/ibus_config.h"
-#include "unix/ibus/main.h"
 #include "unix/ibus/mozc_engine.h"
 #include "unix/ibus/path_util.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(bool, ibus, false, "The engine is started by ibus-daemon");
-MOZC_FLAG(bool, xml, false, "Output xml data for the engine.");
+ABSL_FLAG(bool, ibus, false, "The engine is started by ibus-daemon");
+ABSL_FLAG(bool, xml, false, "Output xml data for the engine.");
 
 namespace {
 
@@ -119,13 +120,13 @@ void OutputXml() {
 
 int main(gint argc, gchar **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
-  if (mozc::GetFlag(FLAGS_xml)) {
+  if (absl::GetFlag(FLAGS_xml)) {
     OutputXml();
     return 0;
   }
 
   ibus_init();
-  InitIBusComponent(mozc::GetFlag(FLAGS_ibus));
+  InitIBusComponent(absl::GetFlag(FLAGS_ibus));
 #ifndef MOZC_NO_LOGGING
   EnableVerboseLog();
 #endif  // MOZC_NO_LOGGING
diff --git unix/ibus/main_stub.cc unix/ibus/main_stub.cc
index 48bb490da..29214a801 100644
--- unix/ibus/main_stub.cc
+++ unix/ibus/main_stub.cc
@@ -29,11 +29,11 @@
 
 #include <iostream>
 
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "unix/ibus/ibus_config.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(bool, xml, false, "Output xml data for the engine.");
+ABSL_FLAG(bool, xml, false, "Output xml data for the engine.");
 
 namespace {
 void OutputXml() {
@@ -44,7 +44,7 @@ void OutputXml() {
 
 int main(int argc, char **argv) {
   mozc::InitMozc(argv[0], &argc, &argv);
-  if (mozc::GetFlag(FLAGS_xml)) {
+  if (absl::GetFlag(FLAGS_xml)) {
     OutputXml();
     return 0;
   }
diff --git unix/ibus/mozc_engine.cc unix/ibus/mozc_engine.cc
index be82541b2..8db7fd8c7 100644
--- unix/ibus/mozc_engine.cc
+++ unix/ibus/mozc_engine.cc
@@ -40,7 +40,6 @@
 #include "base/clock.h"
 #include "base/const.h"
 #include "base/file_util.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/singleton.h"
 #include "base/system_util.h"
@@ -58,6 +57,7 @@
 #include "unix/ibus/preedit_handler.h"
 #include "unix/ibus/property_handler.h"
 #include "unix/ibus/surrounding_text_util.h"
+#include "absl/flags/flag.h"
 
 #ifdef ENABLE_GTK_RENDERER
 #include "renderer/renderer_client.h"
@@ -69,7 +69,7 @@
 #endif  // MOZC_ENABLE_X11_SELECTION_MONITOR
 
 #ifdef ENABLE_GTK_RENDERER
-MOZC_FLAG(bool, use_mozc_renderer, true,
+ABSL_FLAG(bool, use_mozc_renderer, true,
           "The engine tries to use mozc_renderer if available.");
 #endif  // ENABLE_GTK_RENDERER
 
@@ -221,7 +221,7 @@ std::unique_ptr<client::ClientInterface> CreateAndConfigureClient() {
 #ifdef ENABLE_GTK_RENDERER
 CandidateWindowHandlerInterface *createGtkCandidateWindowHandler(
     ::mozc::renderer::RendererClient *renderer_client) {
-  if (!mozc::GetFlag(FLAGS_use_mozc_renderer)) {
+  if (!absl::GetFlag(FLAGS_use_mozc_renderer)) {
     return nullptr;
   }
   if (GetEnv("XDG_SESSION_TYPE") == "wayland") {
diff --git usage_stats/BUILD usage_stats/BUILD
index 4f1ce5116..ffc592f0c 100644
--- usage_stats/BUILD
+++ usage_stats/BUILD
@@ -86,7 +86,6 @@ cc_test_mozc(
     deps = [
         ":usage_stats",
         ":usage_stats_proto",
-        "//base:flags",
         "//base:port",
         "//base:system_util",
         "//config:stats_config_util",
@@ -94,6 +93,7 @@ cc_test_mozc(
         "//storage:registry",
         "//storage:storage_interaface",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
@@ -123,12 +123,12 @@ cc_test_mozc(
         ":usage_stats_testing_util",
         ":usage_stats_uploader",
         "//base",
-        "//base:flags",
         "//base:port",
         "//base:system_util",
         "//base:version",
         "//storage:registry",
         "//testing:gunit_main",
+        "@com_google_absl//absl/flags:flag",
     ],
 )
 
diff --git usage_stats/usage_stats.h usage_stats/usage_stats.h
index 8b71d785a..0729d43f2 100644
--- usage_stats/usage_stats.h
+++ usage_stats/usage_stats.h
@@ -80,7 +80,7 @@ class UsageStats {
   // Synchronizes (writes) usage data into disk. Returns false on failure.
   static bool Sync();
 
-  // Clears existing data exept for Integer and Boolean stats.
+  // Clears existing data except for Integer and Boolean stats.
   static void ClearStats();
 
   // Clears all data.
diff --git usage_stats/usage_stats_test.cc usage_stats/usage_stats_test.cc
index 4debfd226..f8d0fea70 100644
--- usage_stats/usage_stats_test.cc
+++ usage_stats/usage_stats_test.cc
@@ -32,7 +32,6 @@
 #include <map>
 #include <string>
 
-#include "base/flags.h"
 #include "base/port.h"
 #include "base/system_util.h"
 #include "config/stats_config_util.h"
@@ -42,6 +41,7 @@
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
 #include "usage_stats/usage_stats.pb.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace usage_stats {
@@ -49,7 +49,7 @@ namespace usage_stats {
 class UsageStatsTest : public ::testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     EXPECT_TRUE(storage::Registry::Clear());
     mozc::config::StatsConfigUtil::SetHandler(&stats_config_util_);
   }
diff --git usage_stats/usage_stats_uploader_test.cc usage_stats/usage_stats_uploader_test.cc
index 9586135c5..fe376c631 100644
--- usage_stats/usage_stats_uploader_test.cc
+++ usage_stats/usage_stats_uploader_test.cc
@@ -35,7 +35,6 @@
 #include <utility>
 #include <vector>
 
-#include "base/flags.h"
 #include "base/port.h"
 #include "base/system_util.h"
 #include "base/version.h"
@@ -43,6 +42,7 @@
 #include "testing/base/public/googletest.h"
 #include "testing/base/public/gunit.h"
 #include "usage_stats/usage_stats.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace usage_stats {
@@ -63,7 +63,7 @@ void SetUpMetaData(uint32 last_upload_time) {
 class UsageStatsUploaderTest : public ::testing::Test {
  protected:
   void SetUp() override {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     EXPECT_TRUE(storage::Registry::Clear());
   }
 
diff --git win32/base/accessible_object_info.h win32/base/accessible_object_info.h
index ade941773..52e69ff85 100644
--- win32/base/accessible_object_info.h
+++ win32/base/accessible_object_info.h
@@ -40,10 +40,10 @@ namespace win32 {
 struct AccessibleObjectInfo {
   AccessibleObjectInfo();
 
-  string role;  // utf8
+  std::string role;  // utf8
   bool is_builtin_role;
-  string name;   // utf8
-  string value;  // utf8
+  std::string name;   // utf8
+  std::string value;  // utf8
 };
 
 }  // namespace win32
diff --git win32/base/browser_info.cc win32/base/browser_info.cc
index 1bccec4e2..4fb1bb0bf 100644
--- win32/base/browser_info.cc
+++ win32/base/browser_info.cc
@@ -113,26 +113,26 @@ bool BrowserInfo::IsInIncognitoMode(
     return false;
   }
 
-  const char *sufix_ja = nullptr;
-  const char *sufix_en = nullptr;
+  const char *suffix_ja = nullptr;
+  const char *suffix_en = nullptr;
   switch (GetBrowerType()) {
     case kBrowserTypeChrome:
-      sufix_ja = "（シークレット モード）";
-      sufix_en = "(Incognito)";
+      suffix_ja = "（シークレット モード）";
+      suffix_en = "(Incognito)";
       break;
     case kBrowserTypeFirefox:
-      sufix_ja = " (プライベートブラウジング)";
-      sufix_en = "(Private Browsing)";
+      suffix_ja = " (プライベートブラウジング)";
+      suffix_en = "(Private Browsing)";
       break;
     case kBrowserTypeIE:
-      sufix_ja = "[InPrivate]";
-      sufix_en = "[InPrivate]";
+      suffix_ja = "[InPrivate]";
+      suffix_en = "[InPrivate]";
       break;
   }
-  if (sufix_ja != nullptr && Util::EndsWith(root_window_name, sufix_ja)) {
+  if (suffix_ja != nullptr && Util::EndsWith(root_window_name, suffix_ja)) {
     return true;
   }
-  if (sufix_en != nullptr && Util::EndsWith(root_window_name, sufix_en)) {
+  if (suffix_en != nullptr && Util::EndsWith(root_window_name, suffix_en)) {
     return true;
   }
   return false;
diff --git win32/base/focus_hierarchy_observer.h win32/base/focus_hierarchy_observer.h
index faa5173a0..beb3e438c 100644
--- win32/base/focus_hierarchy_observer.h
+++ win32/base/focus_hierarchy_observer.h
@@ -46,8 +46,8 @@ class FocusHierarchyObserver {
   struct WindowInfo {
     WindowInfo();
     HWND window_handle;
-    string title;       // utf8
-    string class_name;  // utf8
+    std::string title;       // utf8
+    std::string class_name;  // utf8
     DWORD process_id;
   };
 
@@ -57,7 +57,7 @@ class FocusHierarchyObserver {
   virtual bool IsAbailable() const = 0;
   virtual std::vector<AccessibleObjectInfo> GetUIHierarchy() const = 0;
   virtual std::vector<WindowInfo> GetWindowHierarchy() const = 0;
-  virtual string GetRootWindowName() const = 0;
+  virtual std::string GetRootWindowName() const = 0;
 
   static FocusHierarchyObserver *Create();
   static void OnDllProcessAttach(HINSTANCE module_handle, bool static_loading);
diff --git win32/base/input_dll.h win32/base/input_dll.h
index 4cbaf28e4..4c7204bed 100644
--- win32/base/input_dll.h
+++ win32/base/input_dll.h
@@ -32,7 +32,7 @@
 
 #include <windows.h>
 
-// Structures and flags bellow have not been included header files in Windows
+// Structures and flags below have not been included header files in Windows
 // SDK.  You can see the original source of this information at the following
 // page.
 // - http://msdn.microsoft.com/en-us/library/bb847907.aspx
@@ -183,7 +183,7 @@ extern "C" __declspec(dllimport) BOOL WINAPI
 //     FALSE: An unspecified error occurred.
 //   Observational Facts:
 //     This API seems to be designed to modify per user settings, like HKCU,
-//     so that the current user can modify it with his/her privileges.  In
+//     so that the current user can modify it with their privileges.  In
 //     oother words, no administrative privilege is required.
 //     SetDefaultLayoutOrTipUserReg might be a phantom, which only exists in
 //     MSDN Library.
diff --git win32/base/keyevent_handler.cc win32/base/keyevent_handler.cc
index a627b386f..8913706a9 100644
--- win32/base/keyevent_handler.cc
+++ win32/base/keyevent_handler.cc
@@ -521,7 +521,7 @@ bool ConvertToKeyEventMain(const VirtualKey &virtual_key, BYTE scan_code,
   //    VK_A         -> 'a'
   //    VK_A + SHIFT -> '('
   // Unfortunately, the current Mozc protocol cannot handle these cases because
-  // there is serious ambiguity betwen 'Key' and 'Character' in Mozc key
+  // there is serious ambiguity between 'Key' and 'Character' in Mozc key
   // bindings.
   const bool is_vk_alpha =
       ('A' <= virtual_key.virtual_key() && virtual_key.virtual_key() <= 'Z');
@@ -924,7 +924,7 @@ bool KeyEventHandler::ConvertToKeyEvent(
     const InputState &ime_state, const KeyboardStatus &keyboard_status,
     Win32KeyboardInterface *keyboard, mozc::commands::KeyEvent *key) {
   // Since Mozc protocol requires tricky conditions for modifiers, using set
-  // container makes the the main part of key event conversion simple rather
+  // container makes the main part of key event conversion simple rather
   // than using vector-like container.
   std::set<KeyEvent::ModifierKey> modifiers;
   const bool result = ConvertToKeyEventMain(
diff --git win32/base/keyevent_handler_test.cc win32/base/keyevent_handler_test.cc
index e3e326522..86d779c59 100644
--- win32/base/keyevent_handler_test.cc
+++ win32/base/keyevent_handler_test.cc
@@ -27,6 +27,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+#include "win32/base/keyevent_handler.h"
+
 // clang-format off
 #include <windows.h>
 #include <ime.h>
@@ -36,7 +38,6 @@
 #include <memory>
 #include <string>
 
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/system_util.h"
 #include "base/version.h"
@@ -48,7 +49,7 @@
 #include "testing/base/public/gunit.h"
 #include "win32/base/input_state.h"
 #include "win32/base/keyboard.h"
-#include "win32/base/keyevent_handler.h"
+#include "absl/flags/flag.h"
 
 namespace mozc {
 namespace win32 {
@@ -245,7 +246,7 @@ class KeyEventHandlerTest : public testing::Test {
   KeyEventHandlerTest() {}
   virtual ~KeyEventHandlerTest() {}
   virtual void SetUp() {
-    SystemUtil::SetUserProfileDirectory(mozc::GetFlag(FLAGS_test_tmpdir));
+    SystemUtil::SetUserProfileDirectory(absl::GetFlag(FLAGS_test_tmpdir));
     mozc::config::ConfigHandler::GetDefaultConfig(&default_config_);
     mozc::config::ConfigHandler::SetConfig(default_config_);
   }
diff --git win32/base/string_util.h win32/base/string_util.h
index cbedd8c50..49d640e4f 100644
--- win32/base/string_util.h
+++ win32/base/string_util.h
@@ -58,7 +58,7 @@ class StringUtil {
 
   // Returns a UTF8 string converted from the result of KeyToReading.
   // This function is mainly for unittest.
-  static string KeyToReadingA(absl::string_view key);
+  static std::string KeyToReadingA(absl::string_view key);
 
   // Joins all segment strings in |preedit| and returns it.
   static std::wstring ComposePreeditText(
diff --git win32/base/surrogate_pair_observer.h win32/base/surrogate_pair_observer.h
index 911071cc3..702e4932e 100644
--- win32/base/surrogate_pair_observer.h
+++ win32/base/surrogate_pair_observer.h
@@ -44,7 +44,7 @@ class SurrogatePairObserver {
   // Return code which represents the expected action of the IME DLL.
   enum ClientActionType {
     // This key event is not a VK_PACKET-related event.
-    // The the caller must do the default action.
+    // The caller must do the default action.
     DO_DEFAULT_ACTION = 0,
     // This key event is a VK_PACKET-related event.
     // The caller replace the VirtualKey instance with new one which conatins
diff --git win32/base/uninstall_helper.h win32/base/uninstall_helper.h
index dda9d7960..3d9ac63e0 100644
--- win32/base/uninstall_helper.h
+++ win32/base/uninstall_helper.h
@@ -79,7 +79,7 @@ class UninstallHelper {
   // settings.  Please beware that this method touches HKCU hive especially
   // when you call this method from a custom action.  If you call this
   // function from the deferred custom action which does not use
-  // impersonation, it is highly recomended to set true for
+  // impersonation, it is highly recommended to set true for
   // |disable_hkcu_cache| so that HKCU points HKU/.Default as expected.
   static bool EnsureIMEIsRemovedForCurrentUser(bool disable_hkcu_cache);
 
diff --git win32/broker/ime_switcher.cc win32/broker/ime_switcher.cc
index 40d4abea4..e8a6218ff 100644
--- win32/broker/ime_switcher.cc
+++ win32/broker/ime_switcher.cc
@@ -33,7 +33,6 @@
 #include <vector>
 
 #include "base/const.h"
-#include "base/flags.h"
 #include "base/logging.h"
 #include "base/process_mutex.h"
 #include "base/scoped_handle.h"
@@ -45,8 +44,9 @@
 #include "win32/base/imm_registrar.h"
 #include "win32/base/imm_util.h"
 #include "win32/base/migration_util.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(bool, set_default_do_not_ask_again, false,
+ABSL_FLAG(bool, set_default_do_not_ask_again, false,
           "Set true if SetDefaultDialog should not be displayed again.");
 
 namespace mozc {
@@ -144,7 +144,7 @@ int RunSetDefaultWin8() {
     return kErrorLevelGeneralError;
   }
 
-  if (mozc::GetFlag(FLAGS_set_default_do_not_ask_again)) {
+  if (absl::GetFlag(FLAGS_set_default_do_not_ask_again)) {
     if (!ClearCheckDefault()) {
       // Notify the error to user but never treat this as an error.
       NotifyFatalMessage("ClearCheckDefault() failed.", __LINE__);
@@ -183,7 +183,7 @@ int RunSetDefault(int argc, char *argv[]) {
     return kErrorLevelGeneralError;
   }
 
-  if (mozc::GetFlag(FLAGS_set_default_do_not_ask_again)) {
+  if (absl::GetFlag(FLAGS_set_default_do_not_ask_again)) {
     if (!ClearCheckDefault()) {
       // Notify the error to user but never treat this as an error.
       NotifyFatalMessage("ClearCheckDefault() failed.", __LINE__);
diff --git win32/broker/mozc_broker.rc win32/broker/mozc_broker.rc
index 7f625b4e1..8448fbe59 100644
Binary files win32/broker/mozc_broker.rc and win32/broker/mozc_broker.rc differ
diff --git win32/broker/mozc_broker_main.cc win32/broker/mozc_broker_main.cc
index 954c30042..6abd2343d 100644
--- win32/broker/mozc_broker_main.cc
+++ win32/broker/mozc_broker_main.cc
@@ -32,15 +32,15 @@
 #endif  // OS_WIN
 
 #include "base/crash_report_handler.h"
-#include "base/flags.h"
 #include "base/init_mozc.h"
 #include "base/system_util.h"
 #ifdef OS_WIN
 #include "base/winmain.h"
 #endif  // OS_WIN
 #include "config/stats_config_util.h"
+#include "absl/flags/flag.h"
 
-MOZC_FLAG(string, mode, "", "mozc_broker mode");
+ABSL_FLAG(std::string, mode, "", "mozc_broker mode");
 
 #ifdef OS_WIN
 namespace mozc {
@@ -66,13 +66,13 @@ int main(int argc, char *argv[]) {
 
   int result = 0;
 #ifdef OS_WIN
-  if (mozc::GetFlag(FLAGS_mode) == "register_ime") {
+  if (absl::GetFlag(FLAGS_mode) == "register_ime") {
     result = mozc::win32::RunRegisterIME(argc, argv);
-  } else if (mozc::GetFlag(FLAGS_mode) == "set_default") {
+  } else if (absl::GetFlag(FLAGS_mode) == "set_default") {
     result = mozc::win32::RunSetDefault(argc, argv);
-  } else if (mozc::GetFlag(FLAGS_mode) == "unregister_ime") {
+  } else if (absl::GetFlag(FLAGS_mode) == "unregister_ime") {
     result = mozc::win32::RunUnregisterIME(argc, argv);
-  } else if (mozc::GetFlag(FLAGS_mode) == "prelaunch_processes") {
+  } else if (absl::GetFlag(FLAGS_mode) == "prelaunch_processes") {
     result = mozc::win32::RunPrelaunchProcesses(argc, argv);
   }
 #endif  // OS_WIN
diff --git win32/custom_action/custom_action.h win32/custom_action/custom_action.h
index b4f461d4f..8633c32d6 100644
--- win32/custom_action/custom_action.h
+++ win32/custom_action/custom_action.h
@@ -96,7 +96,7 @@ UINT __stdcall InitialInstallationCommit(MSIHANDLE msi_handle);
 // RestoreServiceState.
 // Since they are executed as deferred customs actions and most properties
 // cannot be accessible from a deferred custom action, it is necessary to store
-// these data explictly to CustomCationData.
+// these data explicitly to CustomCationData.
 UINT __stdcall SaveCustomActionData(MSIHANDLE msi_handle);
 
 // Restore the settings of the cache service as it was.
diff --git win32/custom_action/custom_action.rc win32/custom_action/custom_action.rc
index a395f6ee2..5f818c8ce 100644
Binary files win32/custom_action/custom_action.rc and win32/custom_action/custom_action.rc differ
diff --git win32/ime/GoogleIMEJa.rc win32/ime/GoogleIMEJa.rc
index fac32bb7c..5cd73c21f 100644
Binary files win32/ime/GoogleIMEJa.rc and win32/ime/GoogleIMEJa.rc differ
diff --git win32/ime/ime_candidate_info_test.cc win32/ime/ime_candidate_info_test.cc
index 32a2d73f1..2b5c11495 100644
--- win32/ime/ime_candidate_info_test.cc
+++ win32/ime/ime_candidate_info_test.cc
@@ -104,11 +104,11 @@ const int32 kIDs[kNumCandidates] = {
     0, 1, 2, 3, 4, 5, 6, 7, -1, -2, -3, -7, -11,
 };
 
-class ScopedCanidateInfoBuffer {
+class ScopedCandidateInfoBuffer {
  public:
-  explicit ScopedCanidateInfoBuffer(size_t size)
+  explicit ScopedCandidateInfoBuffer(size_t size)
       : header_(static_cast<CANDIDATEINFO *>(Allocate(size))) {}
-  ~ScopedCanidateInfoBuffer() { ::HeapFree(::GetProcessHeap(), 0, header_); }
+  ~ScopedCandidateInfoBuffer() { ::HeapFree(::GetProcessHeap(), 0, header_); }
   const CANDIDATEINFO *header() const { return header_; }
   CANDIDATEINFO *mutable_header() { return header_; }
   const CANDIDATELIST *GetList(int candidate_list_no) const {
@@ -133,7 +133,7 @@ class ScopedCanidateInfoBuffer {
   }
   CANDIDATEINFO *header_;
 
-  DISALLOW_COPY_AND_ASSIGN(ScopedCanidateInfoBuffer);
+  DISALLOW_COPY_AND_ASSIGN(ScopedCandidateInfoBuffer);
 };
 
 // TODO(yukawa): Make a common library for this function.
@@ -529,7 +529,7 @@ TEST(CandidateInfoUtilTest, WriteResultTest) {
   CandidateInfo info;
   EXPECT_TRUE(CandidateInfoUtil::Convert(output, &info));
 
-  ScopedCanidateInfoBuffer buffer(info.candidate_info_size);
+  ScopedCandidateInfoBuffer buffer(info.candidate_info_size);
   CandidateInfoUtil::Write(info, buffer.mutable_header());
 
   EXPECT_CANDIDATEINFO(330, 1, sizeof(CANDIDATEINFO), 0, 0, buffer.header());
@@ -558,7 +558,7 @@ TEST(CandidateInfoUtilTest, PagingEmulation_Issue4077022) {
   CandidateInfo info;
   EXPECT_TRUE(CandidateInfoUtil::Convert(output, &info));
 
-  ScopedCanidateInfoBuffer buffer(info.candidate_info_size);
+  ScopedCandidateInfoBuffer buffer(info.candidate_info_size);
   CandidateInfoUtil::Write(info, buffer.mutable_header());
 
   EXPECT_CANDIDATEINFO(330, 1, sizeof(CANDIDATEINFO), 0, 0, buffer.header());
@@ -573,7 +573,7 @@ TEST(CandidateInfoUtilTest, WriteSafeDefaultTest) {
   CandidateInfo info;
   CandidateInfoUtil::SetSafeDefault(&info);
 
-  ScopedCanidateInfoBuffer buffer(info.candidate_info_size);
+  ScopedCandidateInfoBuffer buffer(info.candidate_info_size);
   CandidateInfoUtil::Write(info, buffer.mutable_header());
 
   EXPECT_CANDIDATEINFO(sizeof(CANDIDATEINFO) + sizeof(CANDIDATELIST), 1,
diff --git win32/ime/ime_composition_string.cc win32/ime/ime_composition_string.cc
index ed1a22fc7..0bdcf5c9c 100644
--- win32/ime/ime_composition_string.cc
+++ win32/ime/ime_composition_string.cc
@@ -116,7 +116,7 @@ bool CompositionString::Update(const mozc::commands::Output &output,
     // In OOo, we need this message to restore caret status.
     // We should not send this null-WM_IME_COMPOSITION when
     // |info.dwResultStrLen != 0|.  Otherwise, the result string will be
-    // commited twice in wordpad.exe.
+    // committed twice in wordpad.exe.
     if (info.dwResultStrLen == 0) {
       messages->push_back(UIMessage(WM_IME_COMPOSITION, 0, 0));
     }
diff --git win32/ime/ime_composition_string.h win32/ime/ime_composition_string.h
index 746eca7a2..50daeec00 100644
--- win32/ime/ime_composition_string.h
+++ win32/ime/ime_composition_string.h
@@ -99,9 +99,9 @@ struct CompositionString {
   FRIEND_TEST(ImeCompositionStringTest,
               EndCompositionWhenCompositionBecomesEmpty);
   FRIEND_TEST(ImeCompositionStringTest,
-              EndCompositionWhenCompositionIsCommited);
+              EndCompositionWhenCompositionIsCommitted);
   FRIEND_TEST(ImeCompositionStringTest,
-              EndCompositionWhenCompositionIsCommitedWithPreedit);
+              EndCompositionWhenCompositionIsCommittedWithPreedit);
   FRIEND_TEST(ImeCompositionStringTest, SpaceKeyWhenIMEIsTurnedOn_Issue3200585);
   FRIEND_TEST(ImeCompositionStringTest, Suggest);
   FRIEND_TEST(ImeCompositionStringTest, Predict);
diff --git win32/ime/ime_composition_string_test.cc win32/ime/ime_composition_string_test.cc
index 68762a37a..0d3cf4e16 100644
--- win32/ime/ime_composition_string_test.cc
+++ win32/ime/ime_composition_string_test.cc
@@ -555,9 +555,9 @@ TEST(ImeCompositionStringTest, EndCompositionWhenCompositionBecomesEmpty) {
   EXPECT_EQ(0, compstr.info.dwResultStrLen);
 }
 
-TEST(ImeCompositionStringTest, EndCompositionWhenCompositionIsCommited) {
+TEST(ImeCompositionStringTest, EndCompositionWhenCompositionIsCommitted) {
   // WM_IME_COMPOSITION should be sent up to once.
-  // Otherwise, the result string will be commited twice in wordpad.exe.
+  // Otherwise, the result string will be committed twice in wordpad.exe.
 
   CompositionString compstr;
   EXPECT_TRUE(compstr.Initialize());
@@ -666,9 +666,9 @@ TEST(ImeCompositionStringTest, SpaceKeyWhenIMEIsTurnedOn_Issue3200585) {
 }
 
 TEST(ImeCompositionStringTest,
-     EndCompositionWhenCompositionIsCommitedWithPreedit) {
+     EndCompositionWhenCompositionIsCommittedWithPreedit) {
   // WM_IME_COMPOSITION should be sent up to once.
-  // Otherwise, the result string will be commited twice in wordpad.exe.
+  // Otherwise, the result string will be committed twice in wordpad.exe.
 
   CompositionString compstr;
   EXPECT_TRUE(compstr.Initialize());
diff --git win32/ime/ime_core.cc win32/ime/ime_core.cc
index e16785268..4cd9cb8c5 100644
--- win32/ime/ime_core.cc
+++ win32/ime/ime_core.cc
@@ -626,7 +626,7 @@ bool ImeCore::UpdateContextMain(HIMC himc, const InputState &next_state,
 
   if (generate_message) {
     // In order to minimize the risk of application compatibility problem,
-    // we might want to send these messages in the the same order to MS-IME.
+    // we might want to send these messages in the same order to MS-IME.
     // See b/3488848 for details.
     std::vector<UIMessage> sorted_messages;
     SortIMEMessages(composition_messages, candidate_messages, previous_open,
diff --git win32/ime/ime_core.h win32/ime/ime_core.h
index 6c998ada7..7be02c79f 100644
--- win32/ime/ime_core.h
+++ win32/ime/ime_core.h
@@ -217,7 +217,7 @@ class ImeCore {
 
   // Returns the target string in UTF8 for the reconversion invoked by IME.
   // Returns an empty string if the target strin is not available.
-  static string GetTextForReconversionFromIME(HIMC himc);
+  static std::string GetTextForReconversionFromIME(HIMC himc);
 
   FRIEND_TEST(ImeCoreTest, TemporalConversionModeMessageOrderTest);
   FRIEND_TEST(ImeCoreTest, CandidateMessageOrderTest);
diff --git win32/ime/ime_language_bar.cc win32/ime/ime_language_bar.cc
index 8a4ca264d..ba5334cbe 100644
--- win32/ime/ime_language_bar.cc
+++ win32/ime/ime_language_bar.cc
@@ -47,7 +47,7 @@ using ATL::CComQIPtr;
 namespace {
 // The GUID of the help menu in the system language bar.
 // TODO(mazda): Confirm this GUID is valid permanently for the system help menu
-// since the GUID was programatically obtained.
+// since the GUID was programmatically obtained.
 // It is confirmed that the GUID is valid on Windows XP SP2 and Windows Vista.
 // {ED9D5450-EBE6-4255-8289-F8A31E687228}
 const GUID kSystemLangBarHelpMenu = {
diff --git win32/ime/ime_language_bar_menu.cc win32/ime/ime_language_bar_menu.cc
index ee1c3ad02..7e2ad5c23 100644
--- win32/ime/ime_language_bar_menu.cc
+++ win32/ime/ime_language_bar_menu.cc
@@ -139,9 +139,9 @@ HICON LoadIconFromResource(HINSTANCE instance, UINT icon_id_for_non_theme,
 
 // Retrieves the bitmap handle loaded by using an icon ID.
 // Returns true if the specified icons is available as bitmaps.
-// Caller can set nullptr for |color| and/or |mask| to represent not to recieve
+// Caller can set nullptr for |color| and/or |mask| to represent not to receive
 // the specified handle even if it exists.  Caller should releases any returned
-// bitmap handle and this function releases any handle which is not recieved
+// bitmap handle and this function releases any handle which is not received
 // by the caller.
 bool LoadIconAsBitmap(HINSTANCE instance, UINT icon_id_for_non_theme,
                       UINT icon_id_for_theme, HBITMAP* color, HBITMAP* mask) {
@@ -260,7 +260,7 @@ STDAPI ImeLangBarMenu::GetInfo(TF_LANGBARITEMINFO* item_info) {
 }
 
 // Implements the ITfLangBarItem::GetStatus() function.
-// This fucntion is called by Windows to retrieve the current status of this
+// This function is called by Windows to retrieve the current status of this
 // button menu.
 STDAPI ImeLangBarMenu::GetStatus(DWORD* status) {
   *status = status_;
@@ -271,7 +271,7 @@ STDAPI ImeLangBarMenu::GetStatus(DWORD* status) {
 // This function is called by Windows to notify the display status of this
 // button menu has been updated.
 STDAPI ImeLangBarMenu::Show(BOOL show) {
-  // Just return becasue this button is always shown, i.e. we do not have to
+  // Just return because this button is always shown, i.e. we do not have to
   // manage the display state of this button menu.
   return E_NOTIMPL;
 }
@@ -295,14 +295,14 @@ STDAPI ImeLangBarMenu::OnClick(TfLBIClick click, POINT point,
 }
 
 // Implements the ITfLangBarItemButton::GetText() function.
-// This function is called by Windows to retrive the text label of this
+// This function is called by Windows to retrieve the text label of this
 // button menu.
 STDAPI ImeLangBarMenu::GetText(BSTR* text) {
   *text = ::SysAllocString(&item_info_.szDescription[0]);
   return (*text ? S_OK : E_OUTOFMEMORY);
 }
 
-// Implements the ITfSource::AdviseSink() funtion.
+// Implements the ITfSource::AdviseSink() function.
 STDAPI ImeLangBarMenu::AdviseSink(REFIID interface_id, IUnknown* unknown,
                                   DWORD* cookie) {
   // Return if the caller tries to start advising any events except the
diff --git win32/ime/ime_ui_visibility_tracker_test.cc win32/ime/ime_ui_visibility_tracker_test.cc
index 7be77ae70..08be7fd0e 100644
--- win32/ime/ime_ui_visibility_tracker_test.cc
+++ win32/ime/ime_ui_visibility_tracker_test.cc
@@ -124,7 +124,7 @@ TEST(ImeUIVisibilityTrackerTest,
 }
 
 // When a user changes the input method by the LangBar, WM_IME_SETCONTEXT will
-// not be sent.  Even in this case, the candiate window can be visible,
+// not be sent.  Even in this case, the candidate window can be visible,
 // without any focus change, which finally invokes ImeSetActiveContext.
 TEST(ImeUIVisibilityTrackerTest,
      CandidateWindowCanBeShownWhenImeIsChangedByLangBar) {
diff --git win32/ime/ime_ui_window.cc win32/ime/ime_ui_window.cc
index b4506aa27..ba37b8e7e 100644
--- win32/ime/ime_ui_window.cc
+++ win32/ime/ime_ui_window.cc
@@ -82,7 +82,7 @@ using WTL::CRect;
 using ::mozc::renderer::win32::Win32RendererClient;
 using ::std::unique_ptr;
 
-// True if the the DLL received DLL_PROCESS_DETACH notification.
+// True if the DLL received DLL_PROCESS_DETACH notification.
 volatile bool g_module_unloaded = false;
 
 // As filed in b/3088049 or b/4271156, the IME module (e.g. GIMEJa.ime) is
@@ -979,7 +979,7 @@ class DefaultUIWindow {
 //   [N] kMessageReceiverMessageName / SELECT_CANDIDATE
 //                      any other message(s)
 //
-//   In this case, messages from [1] to [3] can be removed and and start
+//   In this case, messages from [1] to [3] can be removed and start
 //   handling the message [4] as if it the handler just received it.
 //
 //
@@ -992,7 +992,7 @@ class DefaultUIWindow {
 //   [N] kMessageReceiverMessageName / HIGHLIGHT_CANDIDATE
 //                      any other message(s)
 //
-//   In this case, messages from [1] to [2] can be removed and and start
+//   In this case, messages from [1] to [2] can be removed and start
 //   handling the message [4] as if it the handler just received it.
 //
 //
diff --git win32/tip/tip_candidate_list_test.cc win32/tip/tip_candidate_list_test.cc
index 689a502b7..2cd3c60ed 100644
--- win32/tip/tip_candidate_list_test.cc
+++ win32/tip/tip_candidate_list_test.cc
@@ -108,14 +108,14 @@ std::wstring ToWStr(const CComBSTR &bstr) {
 
 AssertionResult ExpectCandidateString(ULONG expected_index,
                                       const std::wstring &expected_text,
-                                      CComPtr<ITfCandidateString> candiate) {
-  if (candiate == nullptr) {
+                                      CComPtr<ITfCandidateString> candidate) {
+  if (candidate == nullptr) {
     return AssertionFailure() << "|actual| should be non-null";
   }
   HRESULT hr = S_OK;
   {
     ULONG index = 0;
-    hr = candiate->GetIndex(&index);
+    hr = candidate->GetIndex(&index);
     if (FAILED(hr)) {
       return AssertionFailure() << "ITfCandidateString::GetIndex failed."
                                 << " hr = " << hr;
@@ -127,7 +127,7 @@ AssertionResult ExpectCandidateString(ULONG expected_index,
   }
   {
     CComBSTR str;
-    hr = candiate->GetString(&str);
+    hr = candidate->GetString(&str);
     if (FAILED(hr)) {
       return AssertionFailure() << "ITfCandidateString::GetString failed."
                                 << " hr = " << hr;
@@ -144,7 +144,7 @@ AssertionResult ExpectCandidateString(ULONG expected_index,
 #define EXPECT_CANDIDATE_STR(expected_index, expected_str, actual) \
   EXPECT_PRED3(ExpectCandidateString, expected_index, expected_str, actual)
 
-TEST(TipCandidateListTest, EmptyCandiate) {
+TEST(TipCandidateListTest, EmptyCandidate) {
   MockCallbackResult result;
 
   std::vector<std::wstring> empty;
@@ -177,7 +177,7 @@ TEST(TipCandidateListTest, EmptyCandiate) {
   EXPECT_FALSE(result.on_finalize_called());
 }
 
-TEST(TipCandidateListTest, NonEmptyCandiates) {
+TEST(TipCandidateListTest, NonEmptyCandidates) {
   MockCallbackResult result;
 
   std::vector<std::wstring> source;
diff --git win32/tip/tip_edit_session_impl.cc win32/tip/tip_edit_session_impl.cc
index 6ad73ed71..e8fcee526 100644
--- win32/tip/tip_edit_session_impl.cc
+++ win32/tip/tip_edit_session_impl.cc
@@ -154,7 +154,7 @@ CComPtr<ITfComposition> CreateComposition(TipTextService *text_service,
 //      interpreted as the "committed text".
 //   4. Update the caret position explicitly. Note that some applications
 //      such as WPF's TextBox do not update the caret position automatically
-//      when an composition is commited.
+//      when an composition is committed.
 // See also b/8406545 and b/9747361.
 CComPtr<ITfComposition> CommitText(TipTextService *text_service,
                                    ITfContext *context,
diff --git win32/tip/tip_lang_bar_menu.cc win32/tip/tip_lang_bar_menu.cc
index 0edc32198..2c715660f 100644
--- win32/tip/tip_lang_bar_menu.cc
+++ win32/tip/tip_lang_bar_menu.cc
@@ -138,9 +138,9 @@ HICON LoadIconFromResource(HINSTANCE instance, UINT icon_id_for_non_theme,
 
 // Retrieves the bitmap handle loaded by using an icon ID.
 // Returns true if the specified icons is available as bitmaps.
-// Caller can set nullptr for |color| and/or |mask| to represent not to recieve
+// Caller can set nullptr for |color| and/or |mask| to represent not to receive
 // the specified handle even if it exists.  Caller should releases any returned
-// bitmap handle and this function releases any handle which is not recieved
+// bitmap handle and this function releases any handle which is not received
 // by the caller.
 bool LoadIconAsBitmap(HINSTANCE instance, UINT icon_id_for_non_theme,
                       UINT icon_id_for_theme, HBITMAP *color, HBITMAP *mask) {
@@ -267,7 +267,7 @@ STDMETHODIMP TipLangBarButton::GetInfo(TF_LANGBARITEMINFO *item_info) {
 }
 
 // Implements the ITfLangBarItem::GetStatus() function.
-// This fucntion is called by Windows to retrieve the current status of this
+// This function is called by Windows to retrieve the current status of this
 // button menu.
 STDMETHODIMP TipLangBarButton::GetStatus(DWORD *status) {
   *status = status_;
@@ -278,7 +278,7 @@ STDMETHODIMP TipLangBarButton::GetStatus(DWORD *status) {
 // This function is called by Windows to notify the display status of this
 // button menu has been updated.
 STDMETHODIMP TipLangBarButton::Show(BOOL show) {
-  // Just return becasue this button is always shown, i.e. we do not have to
+  // Just return because this button is always shown, i.e. we do not have to
   // manage the display state of this button menu.
   return E_NOTIMPL;
 }
@@ -371,14 +371,14 @@ STDMETHODIMP TipLangBarButton::OnClick(TfLBIClick click, POINT point,
 }
 
 // Implements the ITfLangBarItemButton::GetText() function.
-// This function is called by Windows to retrive the text label of this
+// This function is called by Windows to retrieve the text label of this
 // button menu.
 STDMETHODIMP TipLangBarButton::GetText(BSTR *text) {
   *text = ::SysAllocString(&item_info_.szDescription[0]);
   return (*text ? S_OK : E_OUTOFMEMORY);
 }
 
-// Implements the ITfSource::AdviseSink() funtion.
+// Implements the ITfSource::AdviseSink() function.
 STDMETHODIMP TipLangBarButton::AdviseSink(REFIID interface_id,
                                           IUnknown *unknown, DWORD *cookie) {
   // Return if the caller tries to start advising any events except the
diff --git win32/tip/tip_reconvert_function.cc win32/tip/tip_reconvert_function.cc
index 77d408a9c..6f0231153 100644
--- win32/tip/tip_reconvert_function.cc
+++ win32/tip/tip_reconvert_function.cc
@@ -134,7 +134,7 @@ class ReconvertFunctionImpl : public ITfFnReconversion {
   // The ITfFnReconversion interface method.
   virtual HRESULT STDMETHODCALLTYPE QueryRange(ITfRange *range,
                                                ITfRange **new_range,
-                                               BOOL *convertable) {
+                                               BOOL *convertible) {
     if (range == nullptr) {
       return E_INVALIDARG;
     }
@@ -142,10 +142,10 @@ class ReconvertFunctionImpl : public ITfFnReconversion {
       return E_INVALIDARG;
     }
     BOOL dummy_bool = FALSE;
-    if (convertable == nullptr) {
-      convertable = &dummy_bool;
+    if (convertible == nullptr) {
+      convertible = &dummy_bool;
     }
-    *convertable = FALSE;
+    *convertible = FALSE;
     *new_range = nullptr;
 
     CComPtr<ITfContext> context;
@@ -160,7 +160,7 @@ class ReconvertFunctionImpl : public ITfFnReconversion {
 
     if (info.in_composition) {
       // on-going composition is found.
-      *convertable = FALSE;
+      *convertible = FALSE;
       *new_range = nullptr;
       return S_OK;
     }
@@ -168,7 +168,7 @@ class ReconvertFunctionImpl : public ITfFnReconversion {
     if (info.selected_text.find(static_cast<wchar_t>(TS_CHAR_EMBEDDED)) !=
         std::wstring::npos) {
       // embedded object is found.
-      *convertable = FALSE;
+      *convertible = FALSE;
       *new_range = nullptr;
       return S_OK;
     }
@@ -176,7 +176,7 @@ class ReconvertFunctionImpl : public ITfFnReconversion {
     if (FAILED(range->Clone(new_range))) {
       return E_FAIL;
     }
-    *convertable = TRUE;
+    *convertible = TRUE;
     return S_OK;
   }
 
diff --git win32/tip/tip_resource.rc win32/tip/tip_resource.rc
index d9b24ea7e..640277e0d 100644
Binary files win32/tip/tip_resource.rc and win32/tip/tip_resource.rc differ
diff --git win32/tip/tip_surrounding_text.cc win32/tip/tip_surrounding_text.cc
index d42c065c0..ed5f9235d 100644
--- win32/tip/tip_surrounding_text.cc
+++ win32/tip/tip_surrounding_text.cc
@@ -148,14 +148,14 @@ class SurroudingTextUpdater : public ITfEditSession {
     const TF_HALTCOND halt_cond = {nullptr, TF_ANCHOR_START, TF_HF_OBJECT};
 
     {
-      CComPtr<ITfRange> preceeding_range;
-      LONG preceeding_range_shifted = 0;
-      if (SUCCEEDED(selected_range->Clone(&preceeding_range)) &&
-          SUCCEEDED(preceeding_range->Collapse(edit_cookie, TF_ANCHOR_START)) &&
-          SUCCEEDED(preceeding_range->ShiftStart(
-              edit_cookie, -kMaxSurroundingLength, &preceeding_range_shifted,
+      CComPtr<ITfRange> preceding_range;
+      LONG preceding_range_shifted = 0;
+      if (SUCCEEDED(selected_range->Clone(&preceding_range)) &&
+          SUCCEEDED(preceding_range->Collapse(edit_cookie, TF_ANCHOR_START)) &&
+          SUCCEEDED(preceding_range->ShiftStart(
+              edit_cookie, -kMaxSurroundingLength, &preceding_range_shifted,
               &halt_cond))) {
-        result = TipRangeUtil::GetText(preceeding_range, edit_cookie,
+        result = TipRangeUtil::GetText(preceding_range, edit_cookie,
                                        &result_.preceding_text);
         result_.has_preceding_text = SUCCEEDED(result);
       }
@@ -241,11 +241,11 @@ class PrecedingTextDeleter : public ITfEditSession {
 
     const TF_HALTCOND halt_cond = {nullptr, TF_ANCHOR_START, 0};
 
-    CComPtr<ITfRange> preceeding_range;
-    if (FAILED(selected_range->Clone(&preceeding_range))) {
+    CComPtr<ITfRange> preceding_range;
+    if (FAILED(selected_range->Clone(&preceding_range))) {
       return E_FAIL;
     }
-    if (FAILED(preceeding_range->Collapse(edit_cookie, TF_ANCHOR_START))) {
+    if (FAILED(preceding_range->Collapse(edit_cookie, TF_ANCHOR_START))) {
       return E_FAIL;
     }
 
@@ -256,14 +256,14 @@ class PrecedingTextDeleter : public ITfEditSession {
     }
     const LONG initial_offset_utf16 =
         -static_cast<LONG>(num_characters_in_ucs4_) * 2;
-    LONG preceeding_range_shifted = 0;
-    if (FAILED(preceeding_range->ShiftStart(edit_cookie, initial_offset_utf16,
-                                            &preceeding_range_shifted,
+    LONG preceding_range_shifted = 0;
+    if (FAILED(preceding_range->ShiftStart(edit_cookie, initial_offset_utf16,
+                                            &preceding_range_shifted,
                                             &halt_cond))) {
       return E_FAIL;
     }
     std::wstring total_string;
-    if (FAILED(TipRangeUtil::GetText(preceeding_range, edit_cookie,
+    if (FAILED(TipRangeUtil::GetText(preceding_range, edit_cookie,
                                      &total_string))) {
       return E_FAIL;
     }
@@ -278,15 +278,15 @@ class PrecedingTextDeleter : public ITfEditSession {
     }
 
     const LONG final_offset = total_string.size() - len_in_utf16;
-    if (FAILED(preceeding_range->ShiftStart(edit_cookie, final_offset,
-                                            &preceeding_range_shifted,
+    if (FAILED(preceding_range->ShiftStart(edit_cookie, final_offset,
+                                            &preceding_range_shifted,
                                             &halt_cond))) {
       return E_FAIL;
     }
-    if (final_offset != preceeding_range_shifted) {
+    if (final_offset != preceding_range_shifted) {
       return E_FAIL;
     }
-    if (FAILED(preceeding_range->SetText(edit_cookie, 0, L"", 0))) {
+    if (FAILED(preceding_range->SetText(edit_cookie, 0, L"", 0))) {
       return E_FAIL;
     }
 
diff --git win32/tip/tip_surrounding_text.h win32/tip/tip_surrounding_text.h
index 2c11604ed..86cd131bb 100644
--- win32/tip/tip_surrounding_text.h
+++ win32/tip/tip_surrounding_text.h
@@ -86,7 +86,7 @@ class TipSurroundingText {
                                             TipSurroundingTextInfo *info,
                                             bool *need_async_reconversion);
 
-  // Returns true when succeeds to delete preceeding text from the beginning of
+  // Returns true when succeeds to delete preceding text from the beginning of
   // the selected range.
   // Caveats: |num_characters_to_be_deleted_in_ucs4| is not the number of
   //     elements in UTF16. Beware of surrogate pairs.
diff --git win32/tip/tip_text_service.cc win32/tip/tip_text_service.cc
index eea0b3fe1..8bccab402 100644
--- win32/tip/tip_text_service.cc
+++ win32/tip/tip_text_service.cc
@@ -88,7 +88,7 @@ using ATL::CComQIPtr;
 // Represents the module handle of this module.
 volatile HMODULE g_module = nullptr;
 
-// True if the the DLL received DLL_PROCESS_DETACH notification.
+// True if the DLL received DLL_PROCESS_DETACH notification.
 volatile bool g_module_unloaded = false;
 
 // Thread Local Storage (TLS) index to specify the current UI thread is
@@ -877,7 +877,7 @@ class TipTextServiceImpl : public ITfTextInputProcessorEx,
   virtual HRESULT STDMETHODCALLTYPE OnSetThreadFocus() {
     EnsureKanaLockUnlocked();
 
-    // A temporary workaround for b/24793812.  When previous atempt to
+    // A temporary workaround for b/24793812.  When previous attempt to
     // establish conection failed, retry again as if this was the first attempt.
     // TODO(yukawa): We should give up if this fails a number of times.
     if (WinUtil::IsProcessSandboxed()) {
diff --git win32/tip/tip_ui_element_immersive.cc win32/tip/tip_ui_element_immersive.cc
index 336991bbf..9a2e4ab00 100644
--- win32/tip/tip_ui_element_immersive.cc
+++ win32/tip/tip_ui_element_immersive.cc
@@ -108,7 +108,7 @@ const wchar_t kImmersiveUIWindowClassName[] = L"Mozc Immersive UI Window";
 // Represents the module handle of this module.
 volatile HMODULE g_module = nullptr;
 
-// True if the the DLL received DLL_PROCESS_DETACH notification.
+// True if the DLL received DLL_PROCESS_DETACH notification.
 volatile bool g_module_unloaded = false;
 
 // Thread Local Storage (TLS) index to specify the current UI thread is
diff --git win32/tip/tip_ui_handler_immersive.cc win32/tip/tip_ui_handler_immersive.cc
index f96a01138..4bdeed54e 100644
--- win32/tip/tip_ui_handler_immersive.cc
+++ win32/tip/tip_ui_handler_immersive.cc
@@ -69,7 +69,7 @@ typedef ::mozc::commands::Preedit_Segment::Annotation Annotation;
 // Represents the module handle of this module.
 volatile HMODULE g_module = nullptr;
 
-// True if the the DLL received DLL_PROCESS_DETACH notification.
+// True if the DLL received DLL_PROCESS_DETACH notification.
 volatile bool g_module_unloaded = false;
 
 // Thread Local Storage (TLS) index to specify the current UI thread is