Plumb audio muting state to guest web-contents.

content/public/browser/web_contents_observer.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 CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_OBSERVER_H_
 #define CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_OBSERVER_H_
 
 #include <stdint.h>
 
 #include "base/macros.h"
@@ skipping 379 matching lines @@
   // finished, web_contents() returns nullptr.
   virtual void WebContentsDestroyed() {}
 
   // Called when the user agent override for a WebContents has been changed.
   virtual void UserAgentOverrideSet(const std::string& user_agent) {}
 
   // Invoked when new FaviconURL candidates are received from the renderer
   // process.
   virtual void DidUpdateFaviconURL(const std::vector<FaviconURL>& candidates) {}
 
+  // Invoked when the WebContents is muted/unmuted.
+  virtual void DidUpdateAudioMutingState(bool muted) {}
+
   // Invoked when a pepper plugin creates and shows or destroys a fullscreen
   // RenderWidget.
   virtual void DidShowFullscreenWidget(int routing_id) {}
   virtual void DidDestroyFullscreenWidget(int routing_id) {}
 
   // Invoked when the renderer process has toggled the tab into/out of
   // fullscreen mode.
   virtual void DidToggleFullscreenModeForTab(bool entered_fullscreen) {}
 
   // Invoked when an interstitial page is attached or detached.
@@ skipping 70 matching lines @@
   void ResetWebContents();
 
   WebContentsImpl* web_contents_;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsObserver);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_OBSERVER_H_