Remove reference counting from media::DemuxerStream and friends.

media/filters/chunk_demuxer.cc

Index: media/filters/chunk_demuxer.cc
diff --git a/media/filters/chunk_demuxer.cc b/media/filters/chunk_demuxer.cc
index 3ff3f1c9f3d1bcb73c6706bbd8389f6cafbaf6a8..a443eea4cc5dd91311f11a4556ca85e19ec9a0f3 100644
--- a/media/filters/chunk_demuxer.cc
+++ b/media/filters/chunk_demuxer.cc
@@ -173,6 +173,7 @@ class ChunkDemuxerStream : public DemuxerStream {
                      const LogCB& log_cb);
   ChunkDemuxerStream(const VideoDecoderConfig& video_config,
                      const LogCB& log_cb);
+  virtual ~ChunkDemuxerStream();
 
   void StartWaitingForSeek();
   void Seek(TimeDelta time);
@@ -213,9 +214,6 @@ class ChunkDemuxerStream : public DemuxerStream {
   virtual const AudioDecoderConfig& audio_decoder_config() OVERRIDE;
   virtual const VideoDecoderConfig& video_decoder_config() OVERRIDE;
 
- protected:
-  virtual ~ChunkDemuxerStream();
-
  private:
   enum State {
     RETURNING_DATA_FOR_READS,
@@ -615,18 +613,17 @@ void ChunkDemuxer::Seek(TimeDelta time, const PipelineStatusCB& cb) {
 
 void ChunkDemuxer::OnAudioRendererDisabled() {
   base::AutoLock auto_lock(lock_);
-  audio_ = NULL;
+  audio_.reset();  // XXX: IS THIS OK?

[acolwell GONE FROM CHROMIUM, 2013/04/23 03:20:42]

Unfortunately no. The decoder still has a reference. This needs to outlive the
decoder. Need to add a audio_disabled_ boolean to track this state. The existing
code may actually be quite broken. Basically we don't want buffers to get stored
in the stream and we want the stream to always return EOS for reads.

Do we really encounter this codepath a lot? We may want to rethink this
functionality in general... in another CL. :)

[scherkus (not reviewing), 2013/04/23 18:43:40]

I took a stab at fixing this + added a test, but I don't know enough about
ChunkDemuxer to be confident it won't break in some edge case :|

AFAIK we don't have any UMA stats for how often we hit this scenario.

Thinking out loud... it'd be nice if demuxers didn't have to worry about this.
The only reason why its here is so that demuxers won't keep demuxed audio data
around if we know audio has been disabled.

I wonder if with all the recent audio clean up
AudioRendererImpl::OnRenderError() ever gets called. Heck, we might end up
transparently falling back to a fake audio source!

(this code path used to get hit if, say, running on a Windows VM with sound
cards disabled -- see http://crbug.com/106735 for an example)

Filed http://crbug.com/234708 and annotated Demuxer::OARD() and AR::Initialize()

 }
 
 // Demuxer implementation.
-scoped_refptr<DemuxerStream> ChunkDemuxer::GetStream(
-    DemuxerStream::Type type) {
+DemuxerStream* ChunkDemuxer::GetStream(DemuxerStream::Type type) {
   base::AutoLock auto_lock(lock_);
   if (type == DemuxerStream::VIDEO)
-    return video_;
+    return video_.get();
 
   if (type == DemuxerStream::AUDIO)
-    return audio_;
+    return audio_.get();
 
   return NULL;
 }
@@ -1142,7 +1139,7 @@ bool ChunkDemuxer::OnNewConfigs(bool has_audio, bool has_video,
     if (audio_) {
       success &= audio_->UpdateAudioConfig(audio_config);
     } else {
-      audio_ = new ChunkDemuxerStream(audio_config, log_cb_);
+      audio_.reset(new ChunkDemuxerStream(audio_config, log_cb_));
     }
   }
 
@@ -1150,7 +1147,7 @@ bool ChunkDemuxer::OnNewConfigs(bool has_audio, bool has_video,
     if (video_) {
       success &= video_->UpdateVideoConfig(video_config);
     } else {
-      video_ = new ChunkDemuxerStream(video_config, log_cb_);
+      video_.reset(new ChunkDemuxerStream(video_config, log_cb_));
     }
   }
 
@@ -1169,7 +1166,7 @@ bool ChunkDemuxer::OnAudioBuffers(const StreamParser::BufferQueue& buffers) {
   if (!audio_->Append(buffers))
     return false;
 
-  IncreaseDurationIfNecessary(buffers, audio_);
+  IncreaseDurationIfNecessary(buffers, audio_.get());
   return true;
 }
 
@@ -1184,7 +1181,7 @@ bool ChunkDemuxer::OnVideoBuffers(const StreamParser::BufferQueue& buffers) {
   if (!video_->Append(buffers))
     return false;
 
-  IncreaseDurationIfNecessary(buffers, video_);
+  IncreaseDurationIfNecessary(buffers, video_.get());
   return true;
 }
 
@@ -1227,7 +1224,7 @@ void ChunkDemuxer::UpdateDuration(base::TimeDelta new_duration) {
 
 void ChunkDemuxer::IncreaseDurationIfNecessary(
     const StreamParser::BufferQueue& buffers,
-    const scoped_refptr<ChunkDemuxerStream>& stream) {
+    ChunkDemuxerStream* stream) {
   DCHECK(!buffers.empty());
   if (buffers.back()->GetTimestamp() <= duration_)
     return;