MediaStream audio object graph untangling and clean-ups.

content/renderer/media/webrtc/webrtc_media_stream_adapter.cc

Index: content/renderer/media/webrtc/webrtc_media_stream_adapter.cc
diff --git a/content/renderer/media/webrtc/webrtc_media_stream_adapter.cc b/content/renderer/media/webrtc/webrtc_media_stream_adapter.cc
index 4f5d8347f98068b07e5e0a6aae9514752f4b3592..1f63415df715642ec03c448158c6d87a069b686f 100644
--- a/content/renderer/media/webrtc/webrtc_media_stream_adapter.cc
+++ b/content/renderer/media/webrtc/webrtc_media_stream_adapter.cc
@@ -78,7 +78,7 @@ void WebRtcMediaStreamAdapter::CreateAudioTrack(
   DCHECK_EQ(track.source().type(), blink::WebMediaStreamSource::TypeAudio);
   // A media stream is connected to a peer connection, enable the
   // peer connection mode for the sources.
-  MediaStreamAudioTrack* native_track = MediaStreamAudioTrack::GetTrack(track);
+  MediaStreamAudioTrack* native_track = MediaStreamAudioTrack::From(track);
   if (!native_track) {
     DLOG(ERROR) << "No native track for blink audio track.";
     return;
@@ -92,10 +92,9 @@ void WebRtcMediaStreamAdapter::CreateAudioTrack(
 
   if (native_track->is_local_track()) {
     const blink::WebMediaStreamSource& source = track.source();
-    MediaStreamAudioSource* audio_source =
-        static_cast<MediaStreamAudioSource*>(source.extraData());
-    if (audio_source && audio_source->GetAudioCapturer().get())
-      audio_source->GetAudioCapturer()->EnablePeerConnectionMode();
+    MediaStreamAudioSource* audio_source = MediaStreamAudioSource::From(source);
+    if (audio_source && audio_source->audio_capturer())
+      audio_source->audio_capturer()->EnablePeerConnectionMode();
   }
 
   webrtc_media_stream_->AddTrack(audio_track);