Revert of MediaStream audio object graph untangling and clean-ups.

content/renderer/media/audio_track_recorder.cc

Index: content/renderer/media/audio_track_recorder.cc
diff --git a/content/renderer/media/audio_track_recorder.cc b/content/renderer/media/audio_track_recorder.cc
index 2664d5351b6c48b8006ff1a93e6ba30623d19363..dea0c3deb144de9e57f2676863df2e53c75979a0 100644
--- a/content/renderer/media/audio_track_recorder.cc
+++ b/content/renderer/media/audio_track_recorder.cc
@@ -10,7 +10,6 @@
 #include "base/bind.h"
 #include "base/macros.h"
 #include "base/stl_util.h"
-#include "content/renderer/media/media_stream_audio_track.h"
 #include "media/audio/audio_parameters.h"
 #include "media/base/audio_bus.h"
 #include "media/base/audio_converter.h"
@@ -295,7 +294,7 @@
       encoder_thread_("AudioEncoderThread") {
   DCHECK(main_render_thread_checker_.CalledOnValidThread());
   DCHECK(!track_.isNull());
-  DCHECK(MediaStreamAudioTrack::From(track_));
+  DCHECK(track_.extraData());
 
   // Start the |encoder_thread_|. From this point on, |encoder_| should work
   // only on |encoder_thread_|, as enforced by DCHECKs.