Implement proper synchronization between HW video decode IPC and CommandBuffer.

gpu/command_buffer/service/gpu_scheduler.cc

 // 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.
 
 #include "gpu/command_buffer/service/gpu_scheduler.h"
 
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/debug/trace_event.h"
@@ skipping 255 matching lines @@
 void GpuScheduler::SetScheduledCallback(Callback0::Type* scheduled_callback) {
   scheduled_callback_.reset(scheduled_callback);
 }
 
 Buffer GpuScheduler::GetSharedMemoryBuffer(int32 shm_id) {
   return command_buffer_->GetTransferBuffer(shm_id);
 }
 
 void GpuScheduler::set_token(int32 token) {
   command_buffer_->SetToken(token);
+  if (!set_token_callback_.is_null())
+    set_token_callback_.Run(token);
 }
 
 bool GpuScheduler::SetGetOffset(int32 offset) {
   if (parser_->set_get(offset)) {
     command_buffer_->SetGetOffset(static_cast<int32>(parser_->get()));
     return true;
   }
   return false;
 }
 
@@ skipping 18 matching lines @@
   decoder_->SetSwapBuffersCallback(
       NewCallback(this,
                   &GpuScheduler::WillSwapBuffers));
 }
 
 void GpuScheduler::SetCommandProcessedCallback(
     Callback0::Type* callback) {
   command_processed_callback_.reset(callback);
 }
 
+void GpuScheduler::SetTokenCallback(
+    const base::Callback<void(int32)>& callback) {
+  DCHECK(set_token_callback_.is_null());
+  set_token_callback_ = callback;
+}
+
 void GpuScheduler::ScheduleProcessCommands() {
   MessageLoop::current()->PostTask(
       FROM_HERE,
       method_factory_.NewRunnableMethod(&GpuScheduler::ProcessCommands));
 }
 
 void GpuScheduler::WillResize(gfx::Size size) {
   if (wrapped_resize_callback_.get()) {
     wrapped_resize_callback_->Run(size);
   }
 }
 
 }  // namespace gpu