GpuVideoDecoder not to use DemuxerStream after it's stopped.

media/filters/gpu_video_decoder.cc

Index: media/filters/gpu_video_decoder.cc
diff --git a/media/filters/gpu_video_decoder.cc b/media/filters/gpu_video_decoder.cc
index 71994156880483ffe34186e97aa6ec1715b8c972..1be435fff93980a096f6ed0f14d04387b0c4df97 100644
--- a/media/filters/gpu_video_decoder.cc
+++ b/media/filters/gpu_video_decoder.cc
@@ -107,6 +107,7 @@ void GpuVideoDecoder::Stop(const base::Closure& closure) {
     EnqueueFrameAndTriggerFrameDelivery(VideoFrame::CreateEmptyFrame());
   if (!pending_reset_cb_.is_null())
     base::ResetAndReturn(&pending_reset_cb_).Run();
+  demuxer_stream_ = NULL;
   BindToCurrentLoop(closure).Run();
 }
 
@@ -549,14 +550,30 @@ GpuVideoDecoder::~GpuVideoDecoder() {
   DestroyTextures();
 }
 
+void GpuVideoDecoder::ReadFromDemuxerStream() {
+  DCHECK(gvd_loop_proxy_->BelongsToCurrentThread());
+  DCHECK(demuxer_read_in_progress_);
+
+  // This can happen during the tear-down process. GpuVideoDecoder::Stop()
+  // returns the |pending_read_cb_| immediately without waiting for the demuxer
+  // read to be returned. Therefore, this function could be called even after
+  // the decoder has been stopped.
+  if (!demuxer_stream_) {
+    demuxer_read_in_progress_ = false;
+    return;
+  }
+
+  demuxer_stream_->Read(base::Bind(
+      &GpuVideoDecoder::RequestBufferDecode, this));
+}
+
 void GpuVideoDecoder::EnsureDemuxOrDecode() {
   DCHECK(gvd_loop_proxy_->BelongsToCurrentThread());
   if (demuxer_read_in_progress_)
     return;
   demuxer_read_in_progress_ = true;
   gvd_loop_proxy_->PostTask(FROM_HERE, base::Bind(
-      &DemuxerStream::Read, demuxer_stream_.get(),
-      base::Bind(&GpuVideoDecoder::RequestBufferDecode, this)));
+      &GpuVideoDecoder::ReadFromDemuxerStream, this));

[Ami GONE FROM CHROMIUM, 2013/04/04 03:43:22]

Do you see a reason not to simply run the Read() here, instead of posting it?

[xhwang, 2013/04/04 04:15:23]

I think there are two reasons why we always post:
1) DemuxerStream can return the ReadCB synchronously (See
http://crbug.com/168270). 
2) RequestBufferDecode() calls EnsureDemuxOrDecode() directly. If we don't post,
we'd reentry the DS. 

Now (1) is already fixed. (2) seems can be solved by posting
ReadFromDemuxerStream instead of calling it directly. I'll try it out tomorrow
and update this CL.

[xhwang, 2013/04/04 17:05:33]

Done.

 }
 
 void GpuVideoDecoder::NotifyFlushDone() {