MD History: Update sign in state in data source

chrome/browser/ui/webui/md_history_ui.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_WEBUI_MD_HISTORY_UI_H_
 #define CHROME_BROWSER_UI_WEBUI_MD_HISTORY_UI_H_
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "content/public/browser/web_ui_controller.h"
@@ skipping 27 matching lines @@
   static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
 
   static base::RefCountedMemory* GetFaviconResourceBytes(
       ui::ScaleFactor scale_factor);
 
  private:
   FRIEND_TEST_ALL_PREFIXES(ContinueWhereILeftOffTest, MDHistoryUpgrade);
 
   static bool use_test_title_;
 
+  // Create and get the current valid data source.
+  content::WebUIDataSource* CreateAndGetDataSource();
+
   // Handler for the "menuPromoShown" message from the page. No arguments.
   void HandleMenuPromoShown(const base::ListValue* args);
 
+  // Callback method to update sign in state in data source when profile info
+  // changed.
+  void SignInChanged(bool signed_in);
+
   content::WebUIDataSource* data_source_;  // weak
 
   DISALLOW_COPY_AND_ASSIGN(MdHistoryUI);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_MD_HISTORY_UI_H_