MD History: Update sign in state in data source

chrome/browser/ui/webui/history_ui.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.
 
 #ifndef CHROME_BROWSER_UI_WEBUI_HISTORY_UI_H_
 #define CHROME_BROWSER_UI_WEBUI_HISTORY_UI_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 RefCountedMemory;
 }
 
+namespace content {
+class WebUIDataSource;
+}
+
 class HistoryUI : public content::WebUIController {
  public:
   explicit HistoryUI(content::WebUI* web_ui);
   ~HistoryUI() override;
 
   static base::RefCountedMemory* GetFaviconResourceBytes(
       ui::ScaleFactor scale_factor);
 
  private:
+  // 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<HistoryUI> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(HistoryUI);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_HISTORY_UI_H_