Enable fire-and-forget Destroy of HW video decoder, and misc other improvements.

content/common/gpu/gpu_messages.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Multiply-included message file, hence no include guard here, but see below
 // for a much smaller-than-usual include guard section.
 
 #include <vector>
 #include <string>
 
@@ skipping 478 matching lines @@
 
 // Send flush request to the decoder.
 IPC_MESSAGE_ROUTED1(AcceleratedVideoDecoderMsg_Flush,
                     gpu::ReadWriteTokens) /* tokens */
 
 // Send reset request to the decoder.
 IPC_MESSAGE_ROUTED1(AcceleratedVideoDecoderMsg_Reset,
                     gpu::ReadWriteTokens) /* tokens */
 
 // Send destroy request to the decoder.
-IPC_MESSAGE_ROUTED1(AcceleratedVideoDecoderMsg_Destroy,
-                    gpu::ReadWriteTokens) /* tokens */
+IPC_SYNC_MESSAGE_ROUTED1_0(AcceleratedVideoDecoderMsg_Destroy,
+                           gpu::ReadWriteTokens) /* tokens */
 
 //------------------------------------------------------------------------------
 // Accelerated Video Decoder Host Messages
 // These messages are sent from GPU process to Renderer process.
 // Inform AcceleratedVideoDecoderHost that AcceleratedVideoDecoder has been
 // created.
 
 // Accelerated video decoder has consumed input buffer from transfer buffer.
 IPC_MESSAGE_ROUTED1(AcceleratedVideoDecoderHostMsg_BitstreamBufferProcessed,
                     int32) /* Processed buffer ID */
@@ skipping 18 matching lines @@
                     int32,  /* Bitstream buffer ID */
                     gfx::Size, /* Visible size */
                     gfx::Size) /* Decoded size */
 
 // Confirm decoder has been flushed.
 IPC_MESSAGE_ROUTED0(AcceleratedVideoDecoderHostMsg_FlushDone)
 
 // Confirm decoder has been reset.
 IPC_MESSAGE_ROUTED0(AcceleratedVideoDecoderHostMsg_ResetDone)
 
-// Confirm decoder has been destroyed.
-IPC_MESSAGE_ROUTED0(AcceleratedVideoDecoderHostMsg_DestroyDone)
-
 // Decoder has faced end of stream marker in the stream.
 IPC_MESSAGE_ROUTED0(AcceleratedVideoDecoderHostMsg_EndOfStream)
 
 // Video decoder has encountered an error.
 IPC_MESSAGE_ROUTED1(AcceleratedVideoDecoderHostMsg_ErrorNotification,
                     uint32) /* Error ID */