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

chrome/browser/profiles/profile_impl.cc

 // 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.
 
 #include "chrome/browser/profiles/profile_impl.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
@@ skipping 1050 matching lines @@
       } else {
         std::string cur_locale = g_browser_process->GetApplicationLocale();
         std::string backup_locale =
             GetPrefs()->GetString(prefs::kApplicationLocaleBackup);
         // Profile synchronization takes time and is not completed at that
         // moment at first login.  So we initialize locale preference in steps:
         // (1) first save it to temporary backup;
         // (2) on next login we assume that synchronization is already completed
         //     and we may finalize initialization.
         GetPrefs()->SetString(prefs::kApplicationLocaleBackup, cur_locale);
-        if (!backup_locale.empty())
+        if (!new_locale.empty())
+          GetPrefs()->SetString(prefs::kApplicationLocale, new_locale);
+        else if (!backup_locale.empty())
           GetPrefs()->SetString(prefs::kApplicationLocale, backup_locale);
         do_update_pref = false;
       }
       break;
     }
     case APP_LOCALE_CHANGED_VIA_UNKNOWN:
     default: {
       NOTREACHED();
       break;
     }
@@ skipping 119 matching lines @@
 PrefProxyConfigTracker* ProfileImpl::CreateProxyConfigTracker() {
 #if defined(OS_CHROMEOS)
   if (chromeos::ProfileHelper::IsSigninProfile(this)) {
     return ProxyServiceFactory::CreatePrefProxyConfigTrackerOfLocalState(
         g_browser_process->local_state());
   }
 #endif  // defined(OS_CHROMEOS)
   return ProxyServiceFactory::CreatePrefProxyConfigTrackerOfProfile(
       GetPrefs(), g_browser_process->local_state());
 }