Make tab audible and muted states and cause available for an extension API

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 "base/process/kill.h"
 #include "base/process/process_handle.h"
 #include "content/common/content_export.h"
@@ skipping 235 matching lines @@
   virtual void DidGetUserGesture() {}
 
   // This method is invoked when a RenderViewHost of this WebContents was
   // configured to ignore UI events, and an UI event took place.
   virtual void DidGetIgnoredUIEvent() {}
 
   // These methods are invoked every time the WebContents changes visibility.
   virtual void WasShown() {}
   virtual void WasHidden() {}
 
+  // These methods are invoked when there are changes related to sound.
+  virtual void TabAudible(bool isAudible) {};
+  virtual void TabMuted(bool isMuted, const std::string& cause) {};
+
   // This methods is invoked when the title of the WebContents is set. If the
   // title was explicitly set, |explicit_set| is true, otherwise the title was
   // synthesized and |explicit_set| is false.
   virtual void TitleWasSet(NavigationEntry* entry, bool explicit_set) {}
 
   virtual void AppCacheAccessed(const GURL& manifest_url,
                                 bool blocked_by_policy) {}
 
   // Notification that a plugin has crashed.
   // |plugin_pid| is the process ID identifying the plugin process. Note that
@@ skipping 90 matching lines @@
   void ResetWebContents();
 
   WebContentsImpl* web_contents_;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsObserver);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_OBSERVER_H_