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

chrome/browser/media/media_internals.h

Index: chrome/browser/media/media_internals.h
diff --git a/chrome/browser/media/media_internals.h b/chrome/browser/media/media_internals.h
index 55ea413dc1d737a73ef044aa5ac6f2a2457c8e04..983fa6018295890d8adb3ac07b18432071bd69f7 100644
--- a/chrome/browser/media/media_internals.h
+++ b/chrome/browser/media/media_internals.h
@@ -14,6 +14,7 @@
 #include "content/public/browser/media_observer.h"
 #include "content/public/common/media_stream_request.h"
 
+class AudioStreamIndicator;
 class MediaCaptureDevicesDispatcher;
 class MediaInternalsObserver;
 class MediaStreamCaptureIndicator;
@@ -46,6 +47,8 @@ class MediaInternals : public content::MediaObserver {
   virtual void OnDeleteAudioStream(void* host, int stream_id) OVERRIDE;
   virtual void OnSetAudioStreamPlaying(void* host,
                                        int stream_id,
+                                       int render_process_id,
+                                       int render_view_id,
                                        bool playing) OVERRIDE;
   virtual void OnSetAudioStreamStatus(void* host,
                                       int stream_id,
@@ -83,6 +86,7 @@ class MediaInternals : public content::MediaObserver {
   scoped_refptr<MediaStreamCaptureIndicator> GetMediaStreamCaptureIndicator();
   scoped_refptr<MediaCaptureDevicesDispatcher>
       GetMediaCaptureDevicesDispatcher();
+  AudioStreamIndicator* GetAudioStreamIndicator();
 
  private:
   friend class MediaInternalsTest;
@@ -111,6 +115,7 @@ class MediaInternals : public content::MediaObserver {
   ObserverList<MediaInternalsObserver> observers_;
   scoped_refptr<MediaStreamCaptureIndicator> media_stream_capture_indicator_;
   scoped_refptr<MediaCaptureDevicesDispatcher> media_devices_dispatcher_;
+  scoped_refptr<AudioStreamIndicator> audio_stream_indicator_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaInternals);
 };