Chrome MediaStream VideoTrack implementation.

content/renderer/media/media_stream_center.cc

Index: content/renderer/media/media_stream_center.cc
diff --git a/content/renderer/media/media_stream_center.cc b/content/renderer/media/media_stream_center.cc
index c97851b71af934a1da757d46381c7b5d75036fe1..e623643fb06be4cb31edd23f13949ccb205dc879 100644
--- a/content/renderer/media/media_stream_center.cc
+++ b/content/renderer/media/media_stream_center.cc
@@ -14,7 +14,9 @@
 #include "content/renderer/media/media_stream.h"
 #include "content/renderer/media/media_stream_dependency_factory.h"
 #include "content/renderer/media/media_stream_source.h"
+#include "content/renderer/media/media_stream_video_source.h"
 #include "content/renderer/media/media_stream_video_track.h"
+#include "third_party/WebKit/public/platform/WebMediaConstraints.h"
 #include "third_party/WebKit/public/platform/WebMediaStream.h"
 #include "third_party/WebKit/public/platform/WebMediaStreamCenterClient.h"
 #include "third_party/WebKit/public/platform/WebMediaStreamSource.h"
@@ -46,17 +48,18 @@ void CreateNativeVideoMediaStreamTrack(
   DCHECK(track.extraData() == NULL);
   blink::WebMediaStreamSource source = track.source();
   DCHECK_EQ(source.type(), blink::WebMediaStreamSource::TypeVideo);
-
-  if (!source.extraData()) {
+  MediaStreamVideoSource* native_source =
+      MediaStreamVideoSource::GetVideoSource(source);
+  if (!native_source) {
     // TODO(perkj): Implement support for sources from
     // remote MediaStreams.
     NOTIMPLEMENTED();
     return;
   }
-  MediaStreamTrack* native_track = new MediaStreamVideoTrack(factory);
-  native_track->SetEnabled(track.isEnabled());
-  blink::WebMediaStreamTrack writable_track(track);
-  writable_track.setExtraData(native_track);
+  MediaStreamVideoTrack::CreateVideoTrack(

[Ronghua Wu (Left Chromium), 2014/03/04 01:04:11]

I'm confused, who gets the newly created blink::WebMediaStreamTrack?

Or the return value will be the same as |track|? In which case |track| should
not be const&, i.e |track| is changed.

[perkj_chrome, 2014/03/04 10:44:51]

Good catch - right - this is wrong.... |track| has been created by blink so we
should not create a new one. Simply initialize the chrome version.

[Ronghua Wu (Left Chromium), 2014/03/04 23:50:55]

Not sure if writable_track is the common practice, but being able to change a
const& seems be strange to me.

+      native_source, source.constraints(),
+      MediaStreamVideoSource::ConstraintsCallback(), track.isEnabled(),
+      factory);
 }
 
 void CreateNativeMediaStreamTrack(const blink::WebMediaStreamTrack& track,