MD Settings: About page, add an explicit 'aboutPageReady' signal.

chrome/browser/ui/webui/settings/about_handler.h

 // Copyright 2016 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_SETTINGS_ABOUT_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_SETTINGS_ABOUT_HANDLER_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 48 matching lines @@
                const content::NotificationSource& source,
                const content::NotificationDetails& details) override;
 
   // Returns the browser version as a string.
   static base::string16 BuildBrowserVersionString();
 
  private:
   void OnDeviceAutoUpdatePolicyChanged(const base::Value* previous_policy,
                                        const base::Value* current_policy);
 
+  // Called once the JS page is ready to be called, serves as a signal to the
+  // handler to register C++ observers.
+  void HandlePageReady(const base::ListValue* args);
+
   // Called once when the page has loaded. On ChromeOS, this gets the current
   // update status. On other platforms, it will request and perform an update
   // (if one is available).
   void HandleRefreshUpdateStatus(const base::ListValue* args);
   void RefreshUpdateStatus();
 
 #if defined(OS_MACOSX)
   // Promotes the updater for all users.
   void PromoteUpdater(const base::ListValue* args);
 #endif
@@ skipping 65 matching lines @@
 
   // Used for callbacks.
   base::WeakPtrFactory<AboutHandler> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AboutHandler);
 };
 
 }  // namespace settings
 
 #endif  // CHROME_BROWSER_UI_WEBUI_SETTINGS_ABOUT_HANDLER_H_