Close the shared audio output device when the tab is closed.

content/renderer/media/media_stream_impl.cc

Index: content/renderer/media/media_stream_impl.cc
diff --git a/content/renderer/media/media_stream_impl.cc b/content/renderer/media/media_stream_impl.cc
index 6ce995e26084d8352e8a833bf1ae3f7ff7e43421..9eab908f5f90e64927df8e065b0a605a71145c31 100644
--- a/content/renderer/media/media_stream_impl.cc
+++ b/content/renderer/media/media_stream_impl.cc
@@ -552,6 +552,19 @@ void MediaStreamImpl::FrameWillClose(WebKit::WebFrame* frame) {
       ++request_it;
     }
   }
+
+  // Free the potentially-cached audio renderer.  If we don't do this, the
+  // audio device will be held open after the tab has been closed even though
+  // it's not being used.
+  WebRtcAudioDeviceImpl* audio_device =
+      dependency_factory_->GetWebRtcAudioDevice();
+  if (audio_device) {
+    scoped_refptr<WebRtcAudioRenderer> renderer(audio_device->renderer());
+    if (renderer.get()) {
+      renderer->Stop();  // This will clear the dependency factory's pointer.
+      DCHECK(!audio_device->renderer().get());
+    }
+  }
 }
 
 scoped_refptr<VideoFrameProvider>