mus::GpuService: Support establish GpuChannel asynchronously.

components/mus/public/cpp/lib/gles2_context.cc

 // Copyright 2014 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 "components/mus/public/cpp/gles2_context.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <utility>
@@ skipping 28 matching lines @@
     mojom::CommandBufferPtr command_buffer_ptr;
     gpu->CreateOffscreenGLES2Context(GetProxy(&command_buffer_ptr));
     command_buffer_client_impl_.reset(
         new CommandBufferClientImpl(attribs, std::move(command_buffer_ptr)));
     if (!command_buffer_client_impl_->Initialize())
       return false;
     command_buffer = command_buffer_client_impl_.get();
     gpu_control = command_buffer_client_impl_.get();
   } else {
     scoped_refptr<gpu::GpuChannelHost> gpu_channel_host =
-        GpuService::GetInstance()->EstablishGpuChannel(connector);
+        GpuService::GetInstance()->EstablishGpuChannelSync();
     if (!gpu_channel_host)
       return false;
     gpu::SurfaceHandle surface_handle = gfx::kNullAcceleratedWidget;
     // TODO(penghuang): support shared group.
     gpu::CommandBufferProxyImpl* shared_command_buffer = nullptr;
     gpu::GpuStreamId stream_id = gpu::GpuStreamId::GPU_STREAM_DEFAULT;
     gpu::GpuStreamPriority stream_priority = gpu::GpuStreamPriority::NORMAL;
     gl::GpuPreference gpu_preference = gl::PreferIntegratedGpu;
     gpu::gles2::ContextCreationAttribHelper attributes;
     // TODO(penghuang): figure a useful active_url.
@@ skipping 41 matching lines @@
 std::unique_ptr<GLES2Context> GLES2Context::CreateOffscreenContext(
     const std::vector<int32_t>& attribs,
     shell::Connector* connector) {
   std::unique_ptr<GLES2Context> gles2_context(new GLES2Context);
   if (!gles2_context->Initialize(attribs, connector))
     gles2_context.reset();
   return gles2_context;
 }
 
 }  // namespace mus