Made Destroy() followup more aggressive to test for races.

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 378 matching lines @@
                            int32 /* id */,
                            base::SharedMemoryHandle /* transfer_buffer */,
                            uint32 /* size */)
 
 // Create and initialize a hardware video decoder.
 IPC_MESSAGE_ROUTED1(GpuCommandBufferMsg_CreateVideoDecoder,
                     std::vector<uint32> /* configs */)
 
 // Release all resources held by the hardware video decoder associated with this
 // stub.
-IPC_MESSAGE_ROUTED0(GpuCommandBufferMsg_DestroyVideoDecoder)
+IPC_SYNC_MESSAGE_ROUTED0_0(GpuCommandBufferMsg_DestroyVideoDecoder)
 
 // Send from command buffer stub to proxy when window is invalid and must be
 // repainted.
 IPC_MESSAGE_ROUTED0(GpuCommandBufferMsg_NotifyRepaint)
 
 // Tells the GPU process to resize an offscreen frame buffer.
 IPC_MESSAGE_ROUTED1(GpuCommandBufferMsg_ResizeOffscreenFrameBuffer,
                     gfx::Size /* size */)
 
 #if defined(OS_MACOSX)
@@ skipping 121 matching lines @@
 
 // Confirm decoder has been reset.
 IPC_MESSAGE_ROUTED0(AcceleratedVideoDecoderHostMsg_ResetDone)
 
 // 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 */