Introduce new interface for MediaInternals updates.

content/browser/media/media_internals_handler.h

 // Copyright (c) 2011 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 CONTENT_BROWSER_MEDIA_MEDIA_INTERNALS_HANDLER_H_
 #define CONTENT_BROWSER_MEDIA_MEDIA_INTERNALS_HANDLER_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "content/public/browser/web_ui_message_handler.h"
@@ skipping 17 matching lines @@
 
   // Javascript message handlers.
   void OnGetEverything(const base::ListValue* list);
 
   // MediaInternals message handlers.
   void OnUpdate(const string16& update);
 
  private:
   scoped_refptr<MediaInternalsProxy> proxy_;
 
+  // Reflects whether the chrome://media-internals HTML+JS has finished loading.
+  // If not, it's not safe to send JavaScript calls targeting the page yet.
+  bool page_load_complete_;
+
   DISALLOW_COPY_AND_ASSIGN(MediaInternalsMessageHandler);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_MEDIA_MEDIA_INTERNALS_HANDLER_H_