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

chrome/browser/media/media_internals.cc

Index: chrome/browser/media/media_internals.cc
diff --git a/chrome/browser/media/media_internals.cc b/chrome/browser/media/media_internals.cc
index a621160dce33b6b80fc2ec8e70713884bce4d3fa..1f8dce482e4acfa51c25c825f0fa1f27d9999bc5 100644
--- a/chrome/browser/media/media_internals.cc
+++ b/chrome/browser/media/media_internals.cc
@@ -7,6 +7,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/string16.h"
 #include "base/stringprintf.h"
+#include "chrome/browser/media/audio_stream_indicator.h"
 #include "chrome/browser/media/media_capture_devices_dispatcher.h"
 #include "chrome/browser/media/media_internals_observer.h"
 #include "chrome/browser/media/media_stream_capture_indicator.h"
@@ -91,11 +92,17 @@ void MediaInternals::OnDeleteAudioStream(void* host, int stream_id) {
   DeleteItem(stream);
 }
 
-void MediaInternals::OnSetAudioStreamPlaying(
-    void* host, int stream_id, bool playing) {
+void MediaInternals::OnSetAudioStreamPlaying(void* host,
+                                             int stream_id,
+                                             int render_process_id,
+                                             int render_view_id,
+                                             bool playing) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   UpdateAudioStream(host, stream_id,
                     "playing", Value::CreateBooleanValue(playing));
+  audio_stream_indicator_->UpdateWebContentsStatus(render_process_id,
+                                                  render_view_id,

[miu, 2012/12/19 00:49:08]

fix indentation.

+                                                  playing);
 }
 
 void MediaInternals::OnSetAudioStreamStatus(
@@ -199,9 +206,14 @@ MediaInternals::GetMediaStreamCaptureIndicator() {
   return media_stream_capture_indicator_.get();
 }
 
+AudioStreamIndicator* MediaInternals::GetAudioStreamIndicator() {
+  return audio_stream_indicator_;
+}
+
 MediaInternals::MediaInternals()
     : media_stream_capture_indicator_(new MediaStreamCaptureIndicator()),
-      media_devices_dispatcher_(new MediaCaptureDevicesDispatcher()) {
+      media_devices_dispatcher_(new MediaCaptureDevicesDispatcher()),
+      audio_stream_indicator_(new AudioStreamIndicator()) {
 }
 
 void MediaInternals::UpdateAudioStream(