Implement proper synchronization between HW video decode IPC and CommandBuffer.

media/video/video_decode_accelerator.h

Index: media/video/video_decode_accelerator.h
diff --git a/media/video/video_decode_accelerator.h b/media/video/video_decode_accelerator.h
index c50da976f97f88ff471e076ebc91a3133966b116..ab0d471c00e9079443ade8daa2d1cb7b7b443bb3 100644
--- a/media/video/video_decode_accelerator.h
+++ b/media/video/video_decode_accelerator.h
@@ -255,9 +255,7 @@ class VideoDecodeAccelerator {
   // bitstream buffer id.
   // Parameters:
   //  |bitstream_buffer| is the input bitstream that is sent for decoding.
-  //
-  // Returns true when command successfully accepted. Otherwise false.
-  virtual bool Decode(const BitstreamBuffer& bitstream_buffer) = 0;
+  virtual void Decode(const BitstreamBuffer& bitstream_buffer) = 0;
 
   // Assigns a set of picture buffers to the video decoder.
   // AssignGLESBuffers assigns texture-backed buffers.
@@ -285,17 +283,13 @@ class VideoDecodeAccelerator {
   // pictures and buffers held inside the decoder and returning of bitstream
   // buffers using the callbacks implemented by the plug-in. Once done with
   // flushing, the decode will call NotifyFlushDone().
-  //
-  // Returns true when command successfully accepted. Otherwise false.
-  virtual bool Flush() = 0;
+  virtual void Flush() = 0;
 
   // Aborts the decoder. Decode will abort the decoding as soon as possible and
   // will not output anything. NotifyAbortDone() is called  as soon as abort has
   // been finished. After abort all buffers can be considered dismissed, even
   // when there has not been callbacks to dismiss them.
-  //
-  // Returns true when command successfully accepted. Otherwise false.
-  virtual bool Abort() = 0;
+  virtual void Abort() = 0;
 };
 
 }  // namespace media