Move OnDecoderInitDone() from decoder to pipeline thread.

media/filters/audio_renderer_impl.h

Index: media/filters/audio_renderer_impl.h
diff --git a/media/filters/audio_renderer_impl.h b/media/filters/audio_renderer_impl.h
index 47a498b4079ee5f9d59f5fea28c4dbc15ca62980..e9aeece9777ad6132b6966d1ad344415e47431da 100644
--- a/media/filters/audio_renderer_impl.h
+++ b/media/filters/audio_renderer_impl.h
@@ -23,6 +23,7 @@
 #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"
@@ -200,7 +201,10 @@ class MEDIA_EXPORT AudioRendererImpl
   // 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
@@ -227,6 +231,9 @@ class MEDIA_EXPORT AudioRendererImpl
   // 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);
 };