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

chrome/browser/chromeos/login/user_manager_impl.h

Index: chrome/browser/chromeos/login/user_manager_impl.h
diff --git a/chrome/browser/chromeos/login/user_manager_impl.h b/chrome/browser/chromeos/login/user_manager_impl.h
index 41d2e6e7f86214f035be4cc71020e7121c0b1ce0..e3e7eda2bd5243d1ee1646aacd160655ad2bee0b 100644
--- a/chrome/browser/chromeos/login/user_manager_impl.h
+++ b/chrome/browser/chromeos/login/user_manager_impl.h
@@ -79,6 +79,9 @@ class UserManagerImpl
       User::OAuthTokenStatus oauth_token_status) OVERRIDE;
   virtual void SaveUserDisplayName(const std::string& username,
                                    const string16& display_name) OVERRIDE;
+  virtual void UpdateUserAccountData(const std::string& username,
+                                     const string16& display_name,
+                                     const std::string& locale) OVERRIDE;
   virtual string16 GetUserDisplayName(
       const std::string& username) const OVERRIDE;
   virtual void SaveUserDisplayEmail(const std::string& username,
@@ -152,6 +155,9 @@ class UserManagerImpl
   virtual void OnPolicyUpdated(const std::string& user_id) OVERRIDE;
   virtual void OnDeviceLocalAccountsChanged() OVERRIDE;
 
+  // Wait untill we have sufficient information on user locale and apply it.
+  void RespectLocalePreference(Profile* profile, const User* user) const;
+
  private:
   friend class UserManager;
   friend class WallpaperManager;
@@ -302,6 +308,16 @@ class UserManagerImpl
   // Sends metrics in response to a regular user logging in.
   void SendRegularUserLoginMetrics(const std::string& email);
 
+  // UpdateUserAccountData() + SaveUserDisplayName() .
+  void UpdateUserAccountDataImpl(const std::string& username,
+                                 const string16& display_name,
+                                 const std::string* locale);
+
+  // Returns NULL if User is not created.
+  User* GetUserByProfile(Profile* profile) const;
+
+  Profile* GetProfileByUser(const User* user) const;
+
   // Interface to the signed settings store.
   CrosSettings* cros_settings_;