services/ui: GpuService should only be used from a single thread.

services/ui/public/cpp/gpu_service.h

 // Copyright 2016 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.
 
 #ifndef SERVICES_UI_PUBLIC_CPP_GPU_SERVICE_H_
 #define SERVICES_UI_PUBLIC_CPP_GPU_SERVICE_H_
 
 #include <stdint.h>
 #include <vector>
 
@@ skipping 35 matching lines @@
       const gpu::GpuChannelEstablishedCallback& callback) override;
   scoped_refptr<gpu::GpuChannelHost> EstablishGpuChannelSync() override;
   gpu::GpuMemoryBufferManager* GetGpuMemoryBufferManager() override;
 
  private:
   friend struct base::DefaultSingletonTraits<GpuService>;
 
   GpuService(shell::Connector* connector,
              scoped_refptr<base::SingleThreadTaskRunner> task_runner);
 
-  scoped_refptr<gpu::GpuChannelHost> GetGpuChannelLocked();
-  void EstablishGpuChannelOnMainThread();
+  scoped_refptr<gpu::GpuChannelHost> GetGpuChannel();
   void EstablishGpuChannelOnMainThreadSyncLocked();
-  void EstablishGpuChannelOnMainThreadDone(
-      bool locked,
-      int client_id,
-      mojo::ScopedMessagePipeHandle channel_handle,
-      const gpu::GPUInfo& gpu_info);
+  void OnEstablishedGpuChannel(int client_id,
+                               mojo::ScopedMessagePipeHandle channel_handle,
+                               const gpu::GPUInfo& gpu_info);
 
   // gpu::GpuChannelHostFactory overrides:
   bool IsMainThread() override;
   scoped_refptr<base::SingleThreadTaskRunner> GetIOThreadTaskRunner() override;
   std::unique_ptr<base::SharedMemory> AllocateSharedMemory(
       size_t size) override;
 
   scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
   shell::Connector* connector_;
   base::WaitableEvent shutdown_event_;
   std::unique_ptr<base::Thread> io_thread_;
   std::unique_ptr<MojoGpuMemoryBufferManager> gpu_memory_buffer_manager_;
 
-  // Lock for |gpu_channel_|, |establish_callbacks_| & |is_establishing_|.
-  base::Lock lock_;
-  bool is_establishing_;
   ui::mojom::GpuServicePtr gpu_service_;
   scoped_refptr<gpu::GpuChannelHost> gpu_channel_;
   std::vector<gpu::GpuChannelEstablishedCallback> establish_callbacks_;
-  base::ConditionVariable establishing_condition_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuService);
 };
 
 }  // namespace ui
 
 #endif  // SERVICES_UI_PUBLIC_CPP_GPU_SERVICE_H_