Fix a deadlock in the GPU Video decoding code in the renderer which would occur when the renderer

thread was waiting to get the next frame for renderering which attempts to grab the VideoRendererBase lock
and the gpu video decoder thread would wait on the renderer thread to execute a task while holding the above
lock.

Fix is to post task the demuxer_stream_->Read call to ensure that the lock is released by the gpu video decoder
thread.

BUG=129010
R=fischman
Review URL: https://chromiumcodereview.appspot.com/10408043

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@138120 0039d316-1c4b-4281-b951-d872f2087c98

media/filters/gpu_video_decoder.cc

@@ -477,8 +477,9 @@ void GpuVideoDecoder::EnsureDemuxOrDecode() {
   if (demuxer_read_in_progress_)
     return;
   demuxer_read_in_progress_ = true;
-  demuxer_stream_->Read(base::Bind(
-      &GpuVideoDecoder::RequestBufferDecode, this));
+  gvd_loop_proxy_->PostTask(FROM_HERE, base::Bind(
+      &DemuxerStream::Read, demuxer_stream_.get(),
+      base::Bind(&GpuVideoDecoder::RequestBufferDecode, this)));
 }
 
 void GpuVideoDecoder::NotifyFlushDone() {