MediaStream audio object graph untangling and clean-ups.

content/public/renderer/media_stream_audio_sink.cc

Index: content/public/renderer/media_stream_audio_sink.cc
diff --git a/content/public/renderer/media_stream_audio_sink.cc b/content/public/renderer/media_stream_audio_sink.cc
index a6e01a9c7cf47800d30843dcfee8d2e8a0bef984..ad5e12111d72c9e4724aa3d0de2cb8974e2fc90b 100644
--- a/content/public/renderer/media_stream_audio_sink.cc
+++ b/content/public/renderer/media_stream_audio_sink.cc
@@ -15,21 +15,27 @@ void MediaStreamAudioSink::AddToAudioTrack(
     MediaStreamAudioSink* sink,
     const blink::WebMediaStreamTrack& track) {
   DCHECK(track.source().type() == blink::WebMediaStreamSource::TypeAudio);
-  MediaStreamAudioTrack* native_track = MediaStreamAudioTrack::GetTrack(track);
-  native_track->AddSink(sink);
+  if (MediaStreamAudioTrack* native_track = MediaStreamAudioTrack::From(track))
+    native_track->AddSink(sink);
+  else
+    NOTREACHED();
 }
 
 void MediaStreamAudioSink::RemoveFromAudioTrack(
     MediaStreamAudioSink* sink,
     const blink::WebMediaStreamTrack& track) {
-  MediaStreamAudioTrack* native_track = MediaStreamAudioTrack::GetTrack(track);
-  native_track->RemoveSink(sink);
+  if (MediaStreamAudioTrack* native_track = MediaStreamAudioTrack::From(track))
+    native_track->RemoveSink(sink);
+  else
+    NOTREACHED();
 }
 
 media::AudioParameters MediaStreamAudioSink::GetFormatFromAudioTrack(
     const blink::WebMediaStreamTrack& track) {
-  MediaStreamAudioTrack* native_track = MediaStreamAudioTrack::GetTrack(track);
-  return native_track->GetOutputFormat();
+  if (MediaStreamAudioTrack* native_track = MediaStreamAudioTrack::From(track))
+    return native_track->GetOutputFormat();
+  NOTREACHED();
+  return media::AudioParameters();
 }
 
 }  // namespace content