Add an option in language settings for activating the IME menu.

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index 3e5d7ce2f9f25aa7b63d6018b784b848595a28d7..d19e366847001d82dcc920dfb7fb5452c58eeec5 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -505,6 +505,13 @@ const char kLanguageEnabledExtensionImes[] =
 const char kLanguageEnabledExtensionImesSyncable[] =
     "settings.language.enabled_extension_imes_syncable";
 
+// A boolean pref set to true if the 'enable-ime-menu' flag is enabled.
+const char kLangugaeImeMenuFlagEnabled[] =
+    "settings.language.ime_menu_flag_enabled";
+
+// A boolean pref set to true if the IME menu is activated.
+const char kLangugaeImeMenuActivated[] = "settings.language.ime_menu_activated";
+
 // A boolean pref to indicate whether we still need to add the globally synced
 // input methods. False after the initial post-OOBE sync.
 const char kLanguageShouldMergeInputMethods[] =