Enable multilingual spellcheck by default.

This patch enables multilingual spellcheck by default with an option to
disable it on demand via field trial.

BUG=5102

Review URL: https://codereview.chromium.org/1389153002

Cr-Commit-Position: refs/heads/master@{#353107}

17 files changed, 148 insertions, 16 deletions

diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index bb6fe3b..1024afc 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -871,7 +871,8 @@ const Experiment kExperiments[] = {
      IDS_FLAGS_ENABLE_MULTILINGUAL_SPELLCHECKER_NAME,
      IDS_FLAGS_ENABLE_MULTILINGUAL_SPELLCHECKER_DESCRIPTION,
      kOsWin | kOsLinux | kOsCrOS,
-     SINGLE_VALUE_TYPE(switches::kEnableMultilingualSpellChecker)},
+     ENABLE_DISABLE_VALUE_TYPE(switches::kEnableMultilingualSpellChecker,
+                               switches::kDisableMultilingualSpellChecker)},
 #endif
     {"enable-scroll-prediction",
      IDS_FLAGS_ENABLE_SCROLL_PREDICTION_NAME,
diff --git a/chrome/browser/spellchecker/spellcheck_service_browsertest.cc b/chrome/browser/spellchecker/spellcheck_service_browsertest.cc
index 1d6e1e9..55b87bd 100644
--- a/chrome/browser/spellchecker/spellcheck_service_browsertest.cc
+++ b/chrome/browser/spellchecker/spellcheck_service_browsertest.cc
@@ -135,8 +135,7 @@ IN_PROC_BROWSER_TEST_F(SpellcheckServiceBrowserTest, PreferencesNotMigrated) {
 // that all languages get deselected and spellchecking gets enabled.
 IN_PROC_BROWSER_TEST_F(SpellcheckServiceBrowserTest,
                        SpellcheckingDisabledPreferenceMigration) {
-  base::CommandLine::ForCurrentProcess()->AppendSwitch(
-      switches::kEnableMultilingualSpellChecker);
+  ASSERT_TRUE(chrome::spellcheck_common::IsMultilingualSpellcheckEnabled());
 
   PrefService* prefs = user_prefs::UserPrefs::Get(GetContext());
   base::ListValue dictionaries;
@@ -155,6 +154,10 @@ IN_PROC_BROWSER_TEST_F(SpellcheckServiceBrowserTest,
 // multilingual spellchecking.
 IN_PROC_BROWSER_TEST_F(SpellcheckServiceBrowserTest,
                        MultilingualToSingleLanguagePreferenceMigration) {
+  base::CommandLine::ForCurrentProcess()->AppendSwitch(
+      switches::kDisableMultilingualSpellChecker);
+  ASSERT_FALSE(chrome::spellcheck_common::IsMultilingualSpellcheckEnabled());
+
   PrefService* prefs = user_prefs::UserPrefs::Get(GetContext());
   base::ListValue dictionaries;
   dictionaries.AppendString("en-US");
@@ -175,8 +178,7 @@ IN_PROC_BROWSER_TEST_F(SpellcheckServiceBrowserTest,
 // preference stays the same and spellchecking stays enabled.
 IN_PROC_BROWSER_TEST_F(SpellcheckServiceBrowserTest,
                        MultilingualPreferenceNotMigrated) {
-  base::CommandLine::ForCurrentProcess()->AppendSwitch(
-      switches::kEnableMultilingualSpellChecker);
+  ASSERT_TRUE(chrome::spellcheck_common::IsMultilingualSpellcheckEnabled());
 
   PrefService* prefs = user_prefs::UserPrefs::Get(GetContext());
   base::ListValue dictionaries;
@@ -203,6 +205,10 @@ IN_PROC_BROWSER_TEST_F(SpellcheckServiceBrowserTest,
 // the preference should not change.
 IN_PROC_BROWSER_TEST_F(SpellcheckServiceBrowserTest,
                        SingleLanguagePreferenceNotMigrated) {
+  base::CommandLine::ForCurrentProcess()->AppendSwitch(
+      switches::kDisableMultilingualSpellChecker);
+  ASSERT_FALSE(chrome::spellcheck_common::IsMultilingualSpellcheckEnabled());
+
   PrefService* prefs = user_prefs::UserPrefs::Get(GetContext());
   base::ListValue dictionaries;
   dictionaries.AppendString("en-US");
diff --git a/chrome/browser/ui/webui/options/language_options_dictionary_download_browsertest.js b/chrome/browser/ui/webui/options/language_options_dictionary_download_browsertest.js
index e8a5b0f..5a134ec 100644
--- a/chrome/browser/ui/webui/options/language_options_dictionary_download_browsertest.js
+++ b/chrome/browser/ui/webui/options/language_options_dictionary_download_browsertest.js
@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+GEN('#include "chrome/browser/ui/webui/options/' +
+    'single_language_options_browsertest.h"');
+
 /**
  * TestFixture for testing messages of dictionary download progress in language
  * options WebUI.
@@ -18,6 +21,9 @@ LanguagesOptionsDictionaryDownloadWebUITest.prototype = {
    */
   browsePreload: 'chrome://settings-frame/languages',
 
+  /** @override */
+  typedefCppFixture: 'SingleLanguageOptionsBrowserTest',
+
   /**
    * Register a mock dictionary handler.
    */
diff --git a/chrome/browser/ui/webui/options/multilanguage_options_browsertest.cc b/chrome/browser/ui/webui/options/multilanguage_options_browsertest.cc
index da869f5..2ce5747 100644
--- a/chrome/browser/ui/webui/options/multilanguage_options_browsertest.cc
+++ b/chrome/browser/ui/webui/options/multilanguage_options_browsertest.cc
@@ -38,12 +38,6 @@ void MultilanguageOptionsBrowserTest::SetUpOnMainThread() {
                                               std::string());
 }
 
-void MultilanguageOptionsBrowserTest::SetUpCommandLine(
-    base::CommandLine* command_line) {
-  WebUIBrowserTest::SetUpCommandLine(command_line);
-  command_line->AppendSwitch(switches::kEnableMultilingualSpellChecker);
-}
-
 void MultilanguageOptionsBrowserTest::SetDictionariesPref(
     const base::ListValue& value) {
   browser()->profile()->GetPrefs()->Set(prefs::kSpellCheckDictionaries, value);
diff --git a/chrome/browser/ui/webui/options/multilanguage_options_browsertest.h b/chrome/browser/ui/webui/options/multilanguage_options_browsertest.h
index 7f19e17..2ea4c66 100644
--- a/chrome/browser/ui/webui/options/multilanguage_options_browsertest.h
+++ b/chrome/browser/ui/webui/options/multilanguage_options_browsertest.h
@@ -19,7 +19,7 @@ class MultilanguageOptionsBrowserTest : public WebUIBrowserTest {
   void ClearSpellcheckDictionaries();
 
  private:
-  void SetUpCommandLine(base::CommandLine* command_line) override;
+  // WebUIBrowserTest implementation.
   void SetUpOnMainThread() override;
   void SetDictionariesPref(const base::ListValue& value);
 
diff --git a/chrome/browser/ui/webui/options/single_language_options_browsertest.cc b/chrome/browser/ui/webui/options/single_language_options_browsertest.cc
new file mode 100644
index 0000000..50e384e
--- /dev/null
+++ b/chrome/browser/ui/webui/options/single_language_options_browsertest.cc
@@ -0,0 +1,18 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/ui/webui/options/single_language_options_browsertest.h"
+
+#include "base/command_line.h"
+#include "chrome/common/chrome_switches.h"
+
+SingleLanguageOptionsBrowserTest::SingleLanguageOptionsBrowserTest() {}
+
+SingleLanguageOptionsBrowserTest::~SingleLanguageOptionsBrowserTest() {}
+
+void SingleLanguageOptionsBrowserTest::SetUpCommandLine(
+    base::CommandLine* command_line) {
+  WebUIBrowserTest::SetUpCommandLine(command_line);
+  command_line->AppendSwitch(switches::kDisableMultilingualSpellChecker);
+}
diff --git a/chrome/browser/ui/webui/options/single_language_options_browsertest.h b/chrome/browser/ui/webui/options/single_language_options_browsertest.h
new file mode 100644
index 0000000..c992c16
--- /dev/null
+++ b/chrome/browser/ui/webui/options/single_language_options_browsertest.h
@@ -0,0 +1,25 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_UI_WEBUI_OPTIONS_SINGLE_LANGUAGE_OPTIONS_BROWSERTEST_H_
+#define CHROME_BROWSER_UI_WEBUI_OPTIONS_SINGLE_LANGUAGE_OPTIONS_BROWSERTEST_H_
+
+#include "base/macros.h"
+#include "chrome/test/base/web_ui_browser_test.h"
+
+// This is a helper class for language_options_webui_browsertest.js to disable
+// multilingual-spellchecker.
+class SingleLanguageOptionsBrowserTest : public WebUIBrowserTest {
+ public:
+  SingleLanguageOptionsBrowserTest();
+  ~SingleLanguageOptionsBrowserTest() override;
+
+ private:
+  // WebUIBrowserTest implementation.
+  void SetUpCommandLine(base::CommandLine* command_line) override;
+
+  DISALLOW_COPY_AND_ASSIGN(SingleLanguageOptionsBrowserTest);
+};
+
+#endif  // CHROME_BROWSER_UI_WEBUI_OPTIONS_SINGLE_LANGUAGE_OPTIONS_BROWSERTEST_H_
diff --git a/chrome/chrome_tests.gypi b/chrome/chrome_tests.gypi
index 672373d..c23899eb 100644
--- a/chrome/chrome_tests.gypi
+++ b/chrome/chrome_tests.gypi
@@ -564,6 +564,8 @@
       'browser/ui/webui/options/options_browsertest.cc',
       'browser/ui/webui/options/options_ui_browsertest.cc',
       'browser/ui/webui/options/options_ui_browsertest.h',
+      'browser/ui/webui/options/single_language_options_browsertest.cc',
+      'browser/ui/webui/options/single_language_options_browsertest.h',
       'browser/ui/webui/password_manager_internals/password_manager_internals_ui_browsertest.cc',
       'browser/ui/webui/print_preview/print_preview_ui_browsertest.cc',
       'browser/ui/webui/signin/inline_login_ui_browsertest.cc',
diff --git a/chrome/chrome_tests_unit.gypi b/chrome/chrome_tests_unit.gypi
index 0925ca5..3e23671 100644
--- a/chrome/chrome_tests_unit.gypi
+++ b/chrome/chrome_tests_unit.gypi
@@ -570,6 +570,7 @@
       'browser/spellchecker/spellcheck_service_unittest.cc',
       'browser/spellchecker/spelling_service_client_unittest.cc',
       'browser/spellchecker/word_trimmer_unittest.cc',
+      'common/spellcheck_common_unittest.cc',
       'renderer/spellchecker/custom_dictionary_engine_unittest.cc',
       'renderer/spellchecker/spellcheck_multilingual_unittest.cc',
       'renderer/spellchecker/spellcheck_provider_hunspell_unittest.cc',
@@ -2673,6 +2674,7 @@
             '../third_party/libaddressinput/libaddressinput.gyp:libaddressinput',
           ],
           'sources!': [
+            'common/spellcheck_common_unittest.cc',
             'renderer/spellchecker/spellcheck_multilingual_unittest.cc',
             'renderer/spellchecker/spellcheck_provider_hunspell_unittest.cc',
             'renderer/spellchecker/spellcheck_unittest.cc',
diff --git a/chrome/common/OWNERS b/chrome/common/OWNERS
index 3a447e2..a6396e5 100644
--- a/chrome/common/OWNERS
+++ b/chrome/common/OWNERS
@@ -27,8 +27,8 @@ per-file *_messages*.h=wfh@chromium.org
 # Spellcheck files. Not using spellcheck* since it covers IPC messages too.
 per-file spellcheck_bdict_language.h=groby@chromium.org
 per-file spellcheck_bdict_language.h=rouslan@chromium.org
-per-file spellcheck_common.*=groby@chromium.org
-per-file spellcheck_common.*=rouslan@chromium.org
+per-file spellcheck_common*=groby@chromium.org
+per-file spellcheck_common*=rouslan@chromium.org
 per-file spellcheck_marker.h=groby@chromium.org
 per-file spellcheck_marker.h=rouslan@chromium.org
 per-file spellcheck_result.h=groby@chromium.org
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index f82b2f1..189ab43 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -1027,6 +1027,10 @@ const char kSpeculativeResourcePrefetchingEnabled[] = "enabled";
 const char kEnableAndroidSpellChecker[] = "enable-android-spellchecker";
 #endif
 
+// Disables the multilingual spellchecker.
+const char kDisableMultilingualSpellChecker[] =
+    "disable-multilingual-spellchecker";
+
 // Enables the multilingual spellchecker.
 const char kEnableMultilingualSpellChecker[] =
     "enable-multilingual-spellchecker";
diff --git a/chrome/common/chrome_switches.h b/chrome/common/chrome_switches.h
index f66b3d3..7c5691d 100644
--- a/chrome/common/chrome_switches.h
+++ b/chrome/common/chrome_switches.h
@@ -286,6 +286,7 @@ extern const char kSpeculativeResourcePrefetchingLearning[];
 #if defined(OS_ANDROID)
 extern const char kEnableAndroidSpellChecker[];
 #endif
+extern const char kDisableMultilingualSpellChecker[];
 extern const char kEnableMultilingualSpellChecker[];
 extern const char kEnableSpellingAutoCorrect[];
 extern const char kEnableSpellingFeedbackFieldTrial[];
diff --git a/chrome/common/spellcheck_common.cc b/chrome/common/spellcheck_common.cc
index 9aa3a02..cee0883 100644
--- a/chrome/common/spellcheck_common.cc
+++ b/chrome/common/spellcheck_common.cc
@@ -8,6 +8,8 @@
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/macros.h"
+#include "base/metrics/field_trial.h"
+#include "base/strings/string_util.h"
 #include "chrome/common/chrome_switches.h"
 #include "third_party/icu/source/common/unicode/uloc.h"
 #include "third_party/icu/source/common/unicode/urename.h"
@@ -16,6 +18,8 @@
 namespace chrome {
 namespace spellcheck_common {
 
+const char kMultilingualSpellcheckFieldTrial[] = "MultilingualSpellcheck";
+
 struct LanguageRegion {
   const char* language;  // The language.
   const char* language_region;  // language & region, used by dictionaries.
@@ -184,8 +188,21 @@ void GetISOLanguageCountryCodeFromLocale(const std::string& locale,
 }
 
 bool IsMultilingualSpellcheckEnabled() {
-  return base::CommandLine::ForCurrentProcess()->HasSwitch(
-      switches::kEnableMultilingualSpellChecker);
+  // TODO(rouslan): Remove field trial and command line flags when M49 is
+  // stable.
+  const std::string& group_name =
+      base::FieldTrialList::FindFullName(kMultilingualSpellcheckFieldTrial);
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kDisableMultilingualSpellChecker)) {
+    return false;
+  }
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableMultilingualSpellChecker)) {
+    return true;
+  }
+  // Enabled by default, but can be disabled in field trial.
+  return !base::StartsWith(group_name, "Disabled",
+                           base::CompareCase::INSENSITIVE_ASCII);
 }
 
 }  // namespace spellcheck_common
diff --git a/chrome/common/spellcheck_common.h b/chrome/common/spellcheck_common.h
index 7254c8c..deb3617 100644
--- a/chrome/common/spellcheck_common.h
+++ b/chrome/common/spellcheck_common.h
@@ -39,6 +39,9 @@ static const size_t MAX_SYNCABLE_DICTIONARY_WORDS = 1300;
 // dictionary.
 static const size_t MAX_CUSTOM_DICTIONARY_WORD_BYTES = 99;
 
+// The name of the field trial for multilingual spellchecker.
+extern const char kMultilingualSpellcheckFieldTrial[];
+
 base::FilePath GetVersionedFileName(const std::string& input_language,
                                     const base::FilePath& dict_dir);
 
diff --git a/chrome/common/spellcheck_common_unittest.cc b/chrome/common/spellcheck_common_unittest.cc
new file mode 100644
index 0000000..4f877c5
--- /dev/null
+++ b/chrome/common/spellcheck_common_unittest.cc
@@ -0,0 +1,51 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/common/spellcheck_common.h"
+
+#include "base/command_line.h"
+#include "base/metrics/field_trial.h"
+#include "chrome/common/chrome_switches.h"
+#include "components/variations/entropy_provider.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+using chrome::spellcheck_common::IsMultilingualSpellcheckEnabled;
+using chrome::spellcheck_common::kMultilingualSpellcheckFieldTrial;
+
+TEST(SpellcheckCommonTest, MultilingualByDefault) {
+  EXPECT_TRUE(IsMultilingualSpellcheckEnabled());
+}
+
+TEST(SpellcheckCommonTest, CanDisableMultlingualInFieldTrial) {
+  base::FieldTrialList trials(new metrics::SHA1EntropyProvider("foo"));
+  scoped_refptr<base::FieldTrial> trial =
+      base::FieldTrialList::CreateFieldTrial(kMultilingualSpellcheckFieldTrial,
+                                             "Disabled");
+  trial->group();
+
+  EXPECT_FALSE(IsMultilingualSpellcheckEnabled());
+}
+
+TEST(SpellcheckCommonTest, CanDisableMultlingualFromCommandLine) {
+  base::CommandLine::ForCurrentProcess()->AppendSwitch(
+      switches::kDisableMultilingualSpellChecker);
+
+  EXPECT_FALSE(IsMultilingualSpellcheckEnabled());
+}
+
+TEST(SpellcheckCommonTest, CanForceMultlingualFromCommandLine) {
+  base::FieldTrialList trials(new metrics::SHA1EntropyProvider("foo"));
+  scoped_refptr<base::FieldTrial> trial =
+      base::FieldTrialList::CreateFieldTrial(kMultilingualSpellcheckFieldTrial,
+                                             "Disabled");
+  trial->group();
+  base::CommandLine::ForCurrentProcess()->AppendSwitch(
+      switches::kEnableMultilingualSpellChecker);
+
+  EXPECT_TRUE(IsMultilingualSpellcheckEnabled());
+}
+
+}  // namespace
diff --git a/chrome/test/BUILD.gn b/chrome/test/BUILD.gn
index 385948a..cf24c45 100644
--- a/chrome/test/BUILD.gn
+++ b/chrome/test/BUILD.gn
@@ -1204,6 +1204,7 @@ if (!is_android) {
       sources -= [
         "../browser/policy/cloud/component_cloud_policy_browsertest.cc",
         "../browser/prefs/pref_hash_browsertest.cc",
+        "../common/spellcheck_common_unittest.cc",
         "../renderer/spellchecker/spellcheck_provider_hunspell_unittest.cc",
         "../renderer/spellchecker/spellcheck_unittest.cc",
       ]
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 49cb3d3..49717bd 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -64408,6 +64408,7 @@ To add a new entry, add it with any value and run test to compute valid value.
       label="enable-message-center-always-scroll-up-upon-notification-removal"/>
   <int value="1862207743" label="enable-android-spellchecker"/>
   <int value="1865799183" label="javascript-harmony"/>
+  <int value="1881036528" label="disable-multilingual-spellchecker"/>
   <int value="1891210939" label="enable-blink-features"/>
   <int value="1892201400" label="enable-password-separated-signin-flow"/>
   <int value="1896456311" label="enable-password-save-in-page-navigation"/>