If user profile doesn't contain language setting, default to his Google account settings.

chrome/browser/profiles/profile_impl.h

 // Copyright (c) 2012 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.
 
 // This class gathers state related to a single user profile.
 
 #ifndef CHROME_BROWSER_PROFILES_PROFILE_IMPL_H_
 #define CHROME_BROWSER_PROFILES_PROFILE_IMPL_H_
 
 #include <string>
@@ skipping 110 matching lines @@
       base::Time time,
       const base::Closure& completion) OVERRIDE;
   virtual GURL GetHomePage() OVERRIDE;
   virtual bool WasCreatedByVersionOrLater(const std::string& version) OVERRIDE;
   virtual void SetExitType(ExitType exit_type) OVERRIDE;
   virtual ExitType GetLastSessionExitType() OVERRIDE;
 
 #if defined(OS_CHROMEOS)
   virtual void ChangeAppLocale(const std::string& locale,
                                AppLocaleChangedVia) OVERRIDE;
+  virtual void MarkCreated() OVERRIDE;
   virtual void OnLogin() OVERRIDE;
   virtual void SetupChromeOSEnterpriseExtensionObserver() OVERRIDE;
   virtual void InitChromeOSPreferences() OVERRIDE;
+  virtual void RespectLocalePreference() OVERRIDE;
+  virtual void SetGPlusProfileLocale(const std::string& gplus_locale) OVERRIDE;
 #endif  // defined(OS_CHROMEOS)
 
   virtual PrefProxyConfigTracker* GetProxyConfigTracker() OVERRIDE;
 
  private:
   friend class Profile;
   friend class BetterSessionRestoreCrashTest;
   FRIEND_TEST_ALL_PREFIXES(StartupBrowserCreatorTest,
                            ProfilesLaunchedAfterCrash);
   FRIEND_TEST_ALL_PREFIXES(ProfileBrowserTest, ProfileReadmeCreated);
@@ skipping 39 matching lines @@
 
   void UpdateProfileUserNameCache();
 
   // Updates the ProfileInfoCache with data from this profile.
   void UpdateProfileNameCache();
   void UpdateProfileAvatarCache();
 
   void GetCacheParameters(bool is_media_context,
                           base::FilePath* cache_path,
                           int* max_size);
+#if defined(OS_CHROMEOS)

[sail, 2013/08/23 17:08:48]

I really dislike adding new ifdefs to the code. The best way to add new platform
specific code is to have it in a platform specific file. Something like:
  my_profile_locale_cros.cc

[Alexander Alekseev, 2013/09/06 19:52:08]

Done.

+  void ChangeAppLocaleWnenEmpty(const std::string& new_locale);
+#endif
 
   PrefProxyConfigTracker* CreateProxyConfigTracker();
 
   content::HostZoomMap::ZoomLevelChangedCallback zoom_callback_;
   PrefChangeRegistrar pref_change_registrar_;
 
   base::FilePath path_;
   base::FilePath base_cache_path_;
 
   // !!! BIG HONKING WARNING !!!
@@ skipping 40 matching lines @@
 
   scoped_refptr<history::TopSites> top_sites_;  // For history and thumbnails.
 
 #if defined(OS_CHROMEOS)
   scoped_ptr<chromeos::Preferences> chromeos_preferences_;
 
   scoped_ptr<chromeos::EnterpriseExtensionObserver>
       chromeos_enterprise_extension_observer_;
 
   scoped_ptr<chromeos::LocaleChangeGuard> locale_change_guard_;
+
+  bool is_created_;
+  scoped_ptr<std::string> gplus_locale_;
 #endif
 
   scoped_ptr<PrefProxyConfigTracker> pref_proxy_config_tracker_;
 
   // STOP!!!! DO NOT ADD ANY MORE ITEMS HERE!!!!
   //
   // Instead, make your Service/Manager/whatever object you're hanging off the
   // Profile use our new BrowserContextKeyedServiceFactory system instead.
   // You can find the design document here:
   //
   //   https://sites.google.com/a/chromium.org/dev/developers/design-documents/profile-architecture
   //
   // and you can read the raw headers here:
   //
   //   components/browser_context_keyed_service/browser_context_dependency_manager.{h,cc}
   //   components/browser_context_keyed_service/browser_context_keyed_service.h
   //   components/browser_context_keyed_service/browser_context_keyed_service_factory.{h,cc}
 
   Profile::Delegate* delegate_;
 
   chrome_browser_net::Predictor* predictor_;
 
   DISALLOW_COPY_AND_ASSIGN(ProfileImpl);
 };
 
 #endif  // CHROME_BROWSER_PROFILES_PROFILE_IMPL_H_