Reland: Remove reference counting from media::VideoDecoder and friends.

media/filters/ffmpeg_video_decoder.cc

Index: media/filters/ffmpeg_video_decoder.cc
diff --git a/media/filters/ffmpeg_video_decoder.cc b/media/filters/ffmpeg_video_decoder.cc
index 9dd4058513cff2f0d9a5b10b9983f44ba8373f64..105199f197660c4095dd5ac74e0a0bf9cfc60ab7 100644
--- a/media/filters/ffmpeg_video_decoder.cc
+++ b/media/filters/ffmpeg_video_decoder.cc
@@ -58,6 +58,7 @@ static int GetThreadCount(CodecID codec_id) {
 FFmpegVideoDecoder::FFmpegVideoDecoder(
     const scoped_refptr<base::MessageLoopProxy>& message_loop)
     : message_loop_(message_loop),
+      weak_factory_(this),
       state_(kUninitialized),
       codec_context_(NULL),
       av_frame_(NULL) {
@@ -134,6 +135,7 @@ void FFmpegVideoDecoder::Initialize(const scoped_refptr<DemuxerStream>& stream,
                                     const StatisticsCB& statistics_cb) {
   DCHECK(message_loop_->BelongsToCurrentThread());
   PipelineStatusCB initialize_cb = BindToCurrentLoop(status_cb);
+  weak_this_ = weak_factory_.GetWeakPtr();
 
   FFmpegGlue::InitializeFFmpeg();
   DCHECK(!demuxer_stream_) << "Already initialized.";
@@ -224,7 +226,8 @@ void FFmpegVideoDecoder::ReturnFrameOrReadFromDemuxerStream() {
   DCHECK_NE(state_, kUninitialized);
   DCHECK_NE(state_, kDecodeFinished);
   DCHECK(!read_cb_.is_null());
-  demuxer_stream_->Read(base::Bind(&FFmpegVideoDecoder::BufferReady, this));
+  demuxer_stream_->Read(base::Bind(
+      &FFmpegVideoDecoder::BufferReady, weak_this_));
 }
 
 void FFmpegVideoDecoder::BufferReady(