Move OnDecoderInitDone() from decoder to pipeline thread.

media/filters/audio_renderer_impl.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Audio rendering unit utilizing an AudioRendererSink to output data.
 //
 // This class lives inside three threads during it's lifetime, namely:
 // 1. Render thread.
 //    This object is created on the render thread.
 // 2. Pipeline thread
 //    Initialize() is called here with the audio format.
 //    Play/Pause/Preroll() also happens here.
 // 3. Audio thread created by the AudioRendererSink.
 //    Render() is called here where audio data is decoded into raw PCM data.
 //
 // AudioRendererImpl talks to an AudioRendererAlgorithm that takes care of
 // queueing audio data and stretching/shrinking audio data when playback rate !=
 // 1.0 or 0.0.
 
 #ifndef MEDIA_FILTERS_AUDIO_RENDERER_IMPL_H_
 #define MEDIA_FILTERS_AUDIO_RENDERER_IMPL_H_
 
 #include <deque>
 
 #include "base/synchronization/lock.h"
+#include "base/threading/thread_checker.h"
 #include "media/base/audio_decoder.h"
 #include "media/base/audio_renderer.h"
 #include "media/base/audio_renderer_sink.h"
 #include "media/base/buffers.h"
 #include "media/filters/audio_renderer_algorithm.h"
 
 namespace media {
 
 class MEDIA_EXPORT AudioRendererImpl
     : public AudioRenderer,
@@ skipping 154 matching lines @@
   base::Closure underflow_cb_;
   TimeCB time_cb_;
   base::Closure ended_cb_;
   base::Closure disabled_cb_;
   PipelineStatusCB error_cb_;
 
   base::TimeDelta preroll_timestamp_;
 
   uint32 bytes_per_frame_;
 
   // A flag that indicates this filter is called to stop.

[Ami GONE FROM CHROMIUM, 2012/11/01 19:57:01]

doco that this must be only read/written on pipeline_thread_

[DaleCurtis, 2012/11/01 22:02:59]

Removed.

   bool stopped_;

[Ami GONE FROM CHROMIUM, 2012/11/01 19:57:01]

Might be worthwhile to drop stopped_ in favor of clearing sink_ after Stop()ing
it.

[DaleCurtis, 2012/11/01 22:02:59]

Done. The new patch set relies on nothing else being called after Stop() has
completed, which is true as far as I can tell since the stop_cb_ clears the
audio_renderer_ in Pipeline::OnStopCompleted() which is called from
AudioRendererImpl::Stop().

 
-  // The sink (destination) for rendered audio.
+  // The sink (destination) for rendered audio.  |sink_| must only be accessed
+  // on the pipeline thread (verify with |pipeline_thread_checker_|).  |sink_|
+  // must never be called under |lock_| or the 3-way thread bridge between the
+  // audio, pipeline, and decoder threads may dead lock.
   scoped_refptr<media::AudioRendererSink> sink_;
 
   // We're supposed to know amount of audio data OS or hardware buffered, but
   // that is not always so -- on my Linux box
   // AudioBuffersState::hardware_delay_bytes never reaches 0.
   //
   // As a result we cannot use it to find when stream ends. If we just ignore
   // buffered data we will notify host that stream ended before it is actually
   // did so, I've seen it done ~140ms too early when playing ~150ms file.
   //
   // Instead of trying to invent OS-specific solution for each and every OS we
   // are supporting, use simple workaround: every time we fill the buffer we
   // remember when it should stop playing, and do not assume that buffer is
   // empty till that time. Workaround is not bulletproof, as we don't exactly
   // know when that particular data would start playing, but it is much better
   // than nothing.
   base::Time earliest_end_time_;
 
   AudioParameters audio_parameters_;
 
   bool underflow_disabled_;
 
   // True if the renderer receives a buffer with kAborted status during preroll,
   // false otherwise. This flag is cleared on the next Preroll() call.
   bool preroll_aborted_;
 
+  // Ensures certain methods are always called on the pipeline thread.
+  base::ThreadChecker pipeline_thread_checker_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioRendererImpl);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_AUDIO_RENDERER_IMPL_H_