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}

6 files changed, 80 insertions, 4 deletions

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