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 "base/memory/weak_ptr.h"
 #include "content/public/browser/web_ui_controller.h"
 #include "ui/base/layout.h"
 
 class Profile;
 
 namespace base {
 class ListValue;
 class RefCountedMemory;
 }
 
@@ skipping 21 matching lines @@
       ui::ScaleFactor scale_factor);
 
  private:
   FRIEND_TEST_ALL_PREFIXES(ContinueWhereILeftOffTest, MDHistoryUpgrade);
 
   static bool use_test_title_;
 
   // 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
 
+  base::WeakPtrFactory<MdHistoryUI> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(MdHistoryUI);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_MD_HISTORY_UI_H_