Introduce command buffer control thread

mojo/services/gles2/command_buffer_driver.cc

 // Copyright 2013 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 "mojo/services/gles2/command_buffer_driver.h"
 
 #include "base/bind.h"
 #include "base/macros.h"
 #include "base/memory/shared_memory.h"
 #include "gpu/command_buffer/common/constants.h"
@@ skipping 163 matching lines @@
     DVLOG(0) << "Failed to map shared memory.";
     return;
   }
   command_buffer_->RegisterTransferBuffer(id, backing.Pass());
 }
 
 void CommandBufferDriver::DestroyTransferBuffer(int32_t id) {
   command_buffer_->DestroyTransferBuffer(id);
 }
 
+void CommandBufferDriver::Echo(const Callback<void()>& callback) {
+  callback.Run();
+}
+
 void CommandBufferDriver::SetContextLostCallback(
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner,
     const base::Callback<void(int32_t)>& callback) {
+  context_lost_task_runner_ = task_runner;
   context_lost_callback_ = callback;
 }
 
 void CommandBufferDriver::OnParseError() {
   gpu::CommandBuffer::State state = command_buffer_->GetLastState();
   OnContextLost(state.context_lost_reason);
 }
 
 void CommandBufferDriver::OnResize(gfx::Size size, float scale_factor) {
   surface_->Resize(size);
 }
 
 void CommandBufferDriver::OnContextLost(uint32_t reason) {
-  if (!context_lost_callback_.is_null())
-    context_lost_callback_.Run(reason);
+  if (!context_lost_callback_.is_null()) {
+    context_lost_task_runner_->PostTask(
+        FROM_HERE, base::Bind(context_lost_callback_, reason));
+  }
 }
 
 }  // namespace mojo