Implemented Multiple video track recoding.

content/renderer/media/media_recorder_handler.cc

Index: content/renderer/media/media_recorder_handler.cc
diff --git a/content/renderer/media/media_recorder_handler.cc b/content/renderer/media/media_recorder_handler.cc
index d6ef60c9f080883c500f98216cf5fdfab57a9d85..9acc9ec38c680642aec1401806daf9dca0e18404 100644
--- a/content/renderer/media/media_recorder_handler.cc
+++ b/content/renderer/media/media_recorder_handler.cc
@@ -76,22 +76,20 @@ bool MediaRecorderHandler::start(int timeslice) {
     LOG(WARNING) << "Recording no video tracks is not implemented";
     return false;
   }
-  // TODO(mcasas): The muxer API supports only one video track. Extend it to
-  // several video tracks, see http://crbug.com/528523.
-  LOG_IF(WARNING, video_tracks.size() > 1u) << "Recording multiple video"
-      << " tracks is not implemented.  Only recording first video track.";
-  const blink::WebMediaStreamTrack& video_track = video_tracks[0];
-  if (video_track.isNull())
-    return false;
-
-  const VideoTrackRecorder::OnEncodedVideoCB on_encoded_video_cb =
-      media::BindToCurrentLoop(base::Bind(&MediaRecorderHandler::OnEncodedVideo,
-                                          weak_factory_.GetWeakPtr()));
 
-  video_recorders_.push_back(new VideoTrackRecorder(video_track,
-                                                    on_encoded_video_cb));
+  for (const blink::WebMediaStreamTrack& video_track : video_tracks) {
+    if (video_track.isNull()) {
+      LOG(WARNING) << "|video_track| is null";
+      continue;
+    }
+
+    const VideoTrackRecorder::OnEncodedVideoCB on_encoded_video_cb =
+        media::BindToCurrentLoop(webm_muxer_->GenerateOnEncodedVideoCallback());
+    video_recorders_.push_back(
+        new VideoTrackRecorder(video_track, on_encoded_video_cb));
+    recording_ = true;
+  }
 
-  recording_ = true;
   return true;
 }
 
@@ -118,18 +116,6 @@ void MediaRecorderHandler::resume() {
   NOTIMPLEMENTED();
 }
 
-void MediaRecorderHandler::OnEncodedVideo(
-    const scoped_refptr<media::VideoFrame>& video_frame,
-    scoped_ptr<std::string> encoded_data,
-    base::TimeTicks timestamp,
-    bool is_key_frame) {
-  DCHECK(main_render_thread_checker_.CalledOnValidThread());
-  if (webm_muxer_) {
-    webm_muxer_->OnEncodedVideo(video_frame, encoded_data.Pass(), timestamp,
-                                is_key_frame);
-  }
-}
-
 void MediaRecorderHandler::WriteData(base::StringPiece data) {
   DCHECK(main_render_thread_checker_.CalledOnValidThread());
   client_->writeData(data.data(), data.length(), false  /* lastInSlice */);