Implement a source for remote video tracks.

content/renderer/media/media_stream_center.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/media/media_stream_center.h"
 
 #include <string>
 
 #include "base/command_line.h"
 #include "base/logging.h"
@@ skipping 32 matching lines @@
 }
 
 void CreateNativeVideoMediaStreamTrack(
     const blink::WebMediaStreamTrack& track,
     MediaStreamDependencyFactory* factory) {
   DCHECK(track.extraData() == NULL);
   blink::WebMediaStreamSource source = track.source();
   DCHECK_EQ(source.type(), blink::WebMediaStreamSource::TypeVideo);
   MediaStreamVideoSource* native_source =
       MediaStreamVideoSource::GetVideoSource(source);
-  if (!native_source) {
-    // TODO(perkj): Implement support for sources from
-    // remote MediaStreams.
-    NOTIMPLEMENTED();
-    return;
-  }
+  DCHECK(native_source);
   blink::WebMediaStreamTrack writable_track(track);
   writable_track.setExtraData(
       new MediaStreamVideoTrack(native_source, source.constraints(),
                                 MediaStreamVideoSource::ConstraintsCallback(),
                                 track.isEnabled(), factory));
 }
 
 void CreateNativeMediaStreamTrack(const blink::WebMediaStreamTrack& track,
                                   MediaStreamDependencyFactory* factory) {
   DCHECK(!track.isNull() && !track.extraData());
@@ skipping 180 matching lines @@
                     device.type == MEDIA_DEVICE_AUDIO_CAPTURE
                         ? blink::WebSourceInfo::SourceKindAudio
                         : blink::WebSourceInfo::SourceKindVideo,
                     blink::WebString::fromUTF8(device.name),
                     video_facing);
   }
   request_it->second.requestSucceeded(sourceInfos);
 }
 
 }  // namespace content