Add a method to tab_utils.h to find out whether a tab is playing audio.

content/browser/renderer_host/media/mock_media_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_BROWSER_RENDERER_HOST_MEDIA_MOCK_MEDIA_OBSERVER_H_
 #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_MOCK_MEDIA_OBSERVER_H_
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "content/public/browser/media_observer.h"
 #include "media/base/media_log_event.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
 namespace content {
 
 class MockMediaObserver : public MediaObserver {
  public:
   MockMediaObserver();
   virtual ~MockMediaObserver();
 
   MOCK_METHOD2(OnDeleteAudioStream,
                void(void* host, int stream_id));
-  MOCK_METHOD3(OnSetAudioStreamPlaying,
-               void(void* host, int stream_id, bool playing));
+  MOCK_METHOD5(OnSetAudioStreamPlaying,
+               void(void* host, int stream_id, int render_process_id,
+                    int render_view_id, bool playing));
   MOCK_METHOD3(OnSetAudioStreamStatus,
                void(void* host, int stream_id, const std::string& status));
   MOCK_METHOD3(OnSetAudioStreamVolume,
                void(void* host, int stream_id, double volume));
   MOCK_METHOD2(OnMediaEvent,
                void(int source, const media::MediaLogEvent& event));
   MOCK_METHOD3(OnCaptureDevicesOpened,
                void(int render_process_id, int render_view_id,
                     const MediaStreamDevices& devices));
   MOCK_METHOD3(OnCaptureDevicesClosed,
                void(int render_process_id, int render_view_id,
                     const MediaStreamDevices& devices));
   MOCK_METHOD1(OnAudioCaptureDevicesChanged,
                void(const MediaStreamDevices& devices));
   MOCK_METHOD1(OnVideoCaptureDevicesChanged,
                  void(const MediaStreamDevices& devices));
   MOCK_METHOD4(OnMediaRequestStateChanged,
                void(int render_process_id, int render_view_id,
                     const MediaStreamDevice& device,
                     const MediaRequestState state));
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_MOCK_MEDIA_OBSERVER_H_