Update MediaStreamTrack::Stop to latest draft.

content/renderer/media/media_stream_track.cc

Index: content/renderer/media/media_stream_track.cc
diff --git a/content/renderer/media/media_stream_track.cc b/content/renderer/media/media_stream_track.cc
index 1846b17548846d6681e4ec9d1a12b12ab7363611..d823fec333f1a296e747cf23b88dafa56e629c52 100644
--- a/content/renderer/media/media_stream_track.cc
+++ b/content/renderer/media/media_stream_track.cc
@@ -31,6 +31,15 @@ void MediaStreamTrack::SetEnabled(bool enabled) {
     track_->set_enabled(enabled);
 }
 
+void MediaStreamTrack::StopTrack() {
+  // StopTrack means that a track should be stopped permanently. But
+  // since there is no proper way of doing that on a remote track, we can
+  // at least disable the track. Blink will not call down to the content layer
+  // after a track has been stopped.
+  if (track_)
+    track_->set_enabled(false);
+}
+
 webrtc::AudioTrackInterface* MediaStreamTrack::GetAudioAdapter() {
   return static_cast<webrtc::AudioTrackInterface*>(track_.get());
 }