Add VideoTrackSink interface to content/public

content/renderer/media/media_stream_dependency_factory.cc

Index: content/renderer/media/media_stream_dependency_factory.cc
diff --git a/content/renderer/media/media_stream_dependency_factory.cc b/content/renderer/media/media_stream_dependency_factory.cc
index a156d2ebee62a421be8dca6870198e2917714745..6fce0ea2edacb045c1281b673e355bb65c9cc54b 100644
--- a/content/renderer/media/media_stream_dependency_factory.cc
+++ b/content/renderer/media/media_stream_dependency_factory.cc
@@ -19,6 +19,7 @@
 #include "content/renderer/media/rtc_video_decoder_factory.h"
 #include "content/renderer/media/rtc_video_encoder_factory.h"
 #include "content/renderer/media/video_capture_impl_manager.h"
+#include "content/renderer/media/video_track.h"
 #include "content/renderer/media/webaudio_capturer_source.h"
 #include "content/renderer/media/webrtc_audio_device_impl.h"
 #include "content/renderer/media/webrtc_local_audio_track.h"
@@ -864,7 +865,16 @@ void MediaStreamDependencyFactory::AddNativeTrackToBlinkTrack(
     const blink::WebMediaStreamTrack& webkit_track) {
   DCHECK(!webkit_track.isNull() && !webkit_track.extraData());
   blink::WebMediaStreamTrack track = webkit_track;
-  track.setExtraData(new MediaStreamTrackExtraData(native_track));
+
+  if (track.source().type() == blink::WebMediaStreamSource::TypeVideo) {
+    // TODO(perkj): Is it better  to have multiple implementations of
+    // AddNativeTrackToBlinkTrack with different types of |native_track|?
+    DCHECK(native_track->kind() == "video");
+    track.setExtraData(new VideoTrack(
+        static_cast<webrtc::VideoTrackInterface*> (native_track)));
+  } else {
+    track.setExtraData(new MediaStreamTrackExtraData(native_track));
+  }
 }
 
 webrtc::MediaStreamInterface*