WebmMuxer-MediaRecorderHandler: thread hopping and data ownership

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 5934ef9fd11ee121a05e63fa12dcb506736b2ce8..34800585695ae59af9b93cd32485fcb45aa82baa 100644
--- a/content/renderer/media/media_recorder_handler.cc
+++ b/content/renderer/media/media_recorder_handler.cc
@@ -18,6 +18,11 @@ namespace content {
 MediaRecorderHandler::MediaRecorderHandler()
     : recording_(false), client_(nullptr), weak_factory_(this) {
   DVLOG(3) << __FUNCTION__;
+  webm_muxer_ = make_scoped_refptr(
+      new media::WebmMuxer(base::MessageLoop::current()->task_runner(),
+                           media::BindToCurrentLoop(
+                               base::Bind(&MediaRecorderHandler::WriteData,
+                               weak_factory_.GetWeakPtr()))));
 }
 
 MediaRecorderHandler::~MediaRecorderHandler() {
@@ -60,9 +65,6 @@ bool MediaRecorderHandler::start(int timeslice) {
   DCHECK(main_render_thread_checker_.CalledOnValidThread());
   DCHECK(!recording_);
   DCHECK(!media_stream_.isNull());
-
-  webm_muxer_.reset(new media::WebmMuxer(media::BindToCurrentLoop(base::Bind(
-      &MediaRecorderHandler::WriteData, weak_factory_.GetWeakPtr()))));
   DCHECK(webm_muxer_);
 
   blink::WebVector<blink::WebMediaStreamTrack> video_tracks;
@@ -84,8 +86,7 @@ bool MediaRecorderHandler::start(int timeslice) {
     return false;
 
   const VideoTrackRecorder::OnEncodedVideoCB on_encoded_video_cb =
-      base::Bind(&media::WebmMuxer::OnEncodedVideo,
-                 base::Unretained(webm_muxer_.get()));
+      base::Bind(&media::WebmMuxer::OnEncodedVideo, webm_muxer_);
 
   video_recorders_.push_back(new VideoTrackRecorder(video_track,
                                                     on_encoded_video_cb));
@@ -100,7 +101,6 @@ void MediaRecorderHandler::stop() {
 
   recording_ = false;
   video_recorders_.clear();
-  webm_muxer_.reset(NULL);
 }
 
 void MediaRecorderHandler::pause() {