Revert of 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 875a635939acdf300d6b3ecf1c510ac759e98d56..ad075d17c0b401fd17b41b949249cb1616f9a1b5 100644
--- a/content/public/renderer/media_stream_audio_sink.cc
+++ b/content/public/renderer/media_stream_audio_sink.cc
@@ -15,23 +15,20 @@
     MediaStreamAudioSink* sink,
     const blink::WebMediaStreamTrack& track) {
   DCHECK(track.source().getType() == blink::WebMediaStreamSource::TypeAudio);
-  MediaStreamAudioTrack* native_track = MediaStreamAudioTrack::From(track);
-  DCHECK(native_track);
+  MediaStreamAudioTrack* native_track = MediaStreamAudioTrack::GetTrack(track);
   native_track->AddSink(sink);
 }
 
 void MediaStreamAudioSink::RemoveFromAudioTrack(
     MediaStreamAudioSink* sink,
     const blink::WebMediaStreamTrack& track) {
-  MediaStreamAudioTrack* native_track = MediaStreamAudioTrack::From(track);
-  DCHECK(native_track);
+  MediaStreamAudioTrack* native_track = MediaStreamAudioTrack::GetTrack(track);
   native_track->RemoveSink(sink);
 }
 
 media::AudioParameters MediaStreamAudioSink::GetFormatFromAudioTrack(
     const blink::WebMediaStreamTrack& track) {
-  MediaStreamAudioTrack* native_track = MediaStreamAudioTrack::From(track);
-  DCHECK(native_track);
+  MediaStreamAudioTrack* native_track = MediaStreamAudioTrack::GetTrack(track);
   return native_track->GetOutputFormat();
 }