media: Introduce Renderer interface and RendererImpl.

media/filters/video_renderer_impl.cc

Index: media/filters/video_renderer_impl.cc
diff --git a/media/filters/video_renderer_impl.cc b/media/filters/video_renderer_impl.cc
index f315b717053521a2c113e75c1dc179900563f067..743fd1d87ce668cfe048d98b5e1dfb9ba4d77d45 100644
--- a/media/filters/video_renderer_impl.cc
+++ b/media/filters/video_renderer_impl.cc
@@ -202,7 +202,7 @@ void VideoRendererImpl::ThreadMain() {
       if (received_end_of_stream_) {
         if (!rendered_end_of_stream_) {
           rendered_end_of_stream_ = true;
-          ended_cb_.Run();
+          task_runner_->PostTask(FROM_HERE, ended_cb_);
         }
       } else {
         buffering_state_ = BUFFERING_HAVE_NOTHING;
@@ -283,6 +283,7 @@ void VideoRendererImpl::DropNextReadyFrame_Locked() {
 
 void VideoRendererImpl::FrameReady(VideoFrameStream::Status status,
                                    const scoped_refptr<VideoFrame>& frame) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
   base::AutoLock auto_lock(lock_);
   DCHECK_NE(state_, kUninitialized);
   DCHECK_NE(state_, kFlushed);
@@ -344,6 +345,7 @@ bool VideoRendererImpl::HaveEnoughData_Locked() {
 }
 
 void VideoRendererImpl::TransitionToHaveEnough_Locked() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
   DCHECK_EQ(buffering_state_, BUFFERING_HAVE_NOTHING);
 
   if (received_end_of_stream_)
@@ -372,6 +374,7 @@ void VideoRendererImpl::TransitionToHaveEnough_Locked() {
 
 void VideoRendererImpl::AddReadyFrame_Locked(
     const scoped_refptr<VideoFrame>& frame) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
   lock_.AssertAcquired();
   DCHECK(!frame->end_of_stream());
 
@@ -454,7 +457,7 @@ void VideoRendererImpl::UpdateStatsAndWait_Locked(
     PipelineStatistics statistics;
     statistics.video_frames_decoded = frames_decoded_;
     statistics.video_frames_dropped = frames_dropped_;
-    statistics_cb_.Run(statistics);
+    task_runner_->PostTask(FROM_HERE, base::Bind(statistics_cb_, statistics));
 
     frames_decoded_ = 0;
     frames_dropped_ = 0;