cc: Lock access to |buffers_| in TestGpuMemoryBufferManager

cc/test/test_gpu_memory_buffer_manager.h

 // 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.
 
 #ifndef CC_TEST_TEST_GPU_MEMORY_BUFFER_MANAGER_H_
 #define CC_TEST_TEST_GPU_MEMORY_BUFFER_MANAGER_H_
 
 #include <memory>
 
 #include "base/macros.h"
+#include "base/synchronization/lock.h"
 #include "gpu/command_buffer/client/gpu_memory_buffer_manager.h"
 
 namespace cc {
 
 class TestGpuMemoryBufferManager : public gpu::GpuMemoryBufferManager {
  public:
   TestGpuMemoryBufferManager();
   ~TestGpuMemoryBufferManager() override;
 
   std::unique_ptr<TestGpuMemoryBufferManager>
   CreateClientGpuMemoryBufferManager();
   int GetClientId() { return client_id_; }
 
   void OnGpuMemoryBufferDestroyed(gfx::GpuMemoryBufferId gpu_memory_buffer_id);
 
   // Overridden from gpu::GpuMemoryBufferManager:
   std::unique_ptr<gfx::GpuMemoryBuffer> CreateGpuMemoryBuffer(
       const gfx::Size& size,
       gfx::BufferFormat format,
       gfx::BufferUsage usage,
       gpu::SurfaceHandle surface_handle) override;
   void SetDestructionSyncToken(gfx::GpuMemoryBuffer* buffer,
                                const gpu::SyncToken& sync_token) override;
 
  private:
   // Buffers allocated by this manager.
   int last_gpu_memory_buffer_id_ = 1000;
+  // Use of |buffers_| must be protected by the lock.
+  base::Lock buffers_lock_;
   std::map<int, gfx::GpuMemoryBuffer*> buffers_;
 
   // Parent information for child managers.
   int client_id_ = -1;
   TestGpuMemoryBufferManager* parent_gpu_memory_buffer_manager_ = nullptr;
 
   // Child infomration for parent managers.
   int last_client_id_ = 5000;
   std::map<int, TestGpuMemoryBufferManager*> clients_;
 
   DISALLOW_COPY_AND_ASSIGN(TestGpuMemoryBufferManager);
 };
 
 }  // namespace cc
 
 #endif  // CC_TEST_TEST_GPU_MEMORY_BUFFER_MANAGER_H_