Add Stop() to AudioDecoder.

media/filters/ffmpeg_audio_decoder.cc

Index: media/filters/ffmpeg_audio_decoder.cc
diff --git a/media/filters/ffmpeg_audio_decoder.cc b/media/filters/ffmpeg_audio_decoder.cc
index a0e5889eff11aca7e6c84c6bdbf26080ca2fd8c0..8de9f962a8f2d7d8c8a6940654667759259d31f9 100644
--- a/media/filters/ffmpeg_audio_decoder.cc
+++ b/media/filters/ffmpeg_audio_decoder.cc
@@ -155,12 +155,20 @@ void FFmpegAudioDecoder::Reset(const base::Closure& closure) {
   reset_cb.Run();
 }
 
-FFmpegAudioDecoder::~FFmpegAudioDecoder() {
-  // TODO(scherkus): should we require Stop() to be called? this might end up
-  // getting called on a random thread due to refcounting.
+void FFmpegAudioDecoder::Stop(const base::Closure& closure) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  base::Closure stop_cb = BindToCurrentLoop(closure);
+
+  avcodec_flush_buffers(codec_context_.get());

[DaleCurtis, 2014/01/08 00:30:54]

What made you add this?  We don't make a similar call in the FFmpeg video
decoder for Stop, only during Reset.  I'm not sure it's wrong, I'm just curious.

[rileya (GONE FROM CHROMIUM), 2014/01/08 21:05:50]

I'm not sure actually I think I saw it done in Reset and figured it couldn't
hurt. In any case, I got rid of it.

+  ResetTimestampState();
+  queued_audio_.clear();
   ReleaseFFmpegResources();
+
+  stop_cb.Run();

[xhwang, 2014/01/08 01:33:37]

Here and in Reset(), what if we have |read_cb_| pending? Usually in that case we
should abort the read, then satisfy reset_cb or stop_cb, or defer the reset/stop
process until Demuxer read is back.

You can add a TODO and fix this in another CL.

[rileya (GONE FROM CHROMIUM), 2014/01/08 21:05:50]

I'd wondered about this, added a TODO.

 }
 
+FFmpegAudioDecoder::~FFmpegAudioDecoder() {}
+
 int FFmpegAudioDecoder::GetAudioBuffer(AVCodecContext* codec,
                                        AVFrame* frame,
                                        int flags) {