MD History: Update sign in state in data source

chrome/browser/ui/webui/history_login_handler.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_HISTORY_LOGIN_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_HISTORY_LOGIN_HANDLER_H_
 
 #include <memory>
 
+#include "base/callback_forward.h"
 #include "base/macros.h"
 #include "content/public/browser/web_ui_message_handler.h"
 
 class ProfileInfoWatcher;
 
 // The handler for login-related messages from chrome://history.
 class HistoryLoginHandler : public content::WebUIMessageHandler {
  public:
-  HistoryLoginHandler();
+  explicit HistoryLoginHandler(const base::Closure& signin_callback);
   ~HistoryLoginHandler() override;
 
   // WebUIMessageHandler implementation.
   void RegisterMessages() override;
 
  private:
   // Handler for the "otherDevicesInitialized" message. No args.
   void HandleOtherDevicesInitialized(const base::ListValue* args);
 
   // Handler for the "startSignInFlow" message. No args.
   void HandleStartSignInFlow(const base::ListValue* args);
 
   // Called by |profile_info_watcher_| on desktop if profile info changes.
   void ProfileInfoChanged();
 
   // Watches this web UI's profile for info changes (e.g. authenticated username
   // changes).
   std::unique_ptr<ProfileInfoWatcher> profile_info_watcher_;
 
+  base::Closure signin_callback_;
+
   DISALLOW_COPY_AND_ASSIGN(HistoryLoginHandler);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_HISTORY_LOGIN_HANDLER_H_