gpu: Directly cast ClientBuffer to gfx::GpuMemoryBuffer

ui/aura/mus/mojo_gpu_memory_buffer_manager.h

 // Copyright 2015 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 UI_AURA_MUS_MOJO_GPU_MEMORY_BUFFER_MANAGER_H_
 #define UI_AURA_MUS_MOJO_GPU_MEMORY_BUFFER_MANAGER_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "gpu/command_buffer/client/gpu_memory_buffer_manager.h"
 
 namespace aura {
 
 class MojoGpuMemoryBufferManager : public gpu::GpuMemoryBufferManager {
  public:
   MojoGpuMemoryBufferManager();
   ~MojoGpuMemoryBufferManager() override;
 
   // Overridden from gpu::GpuMemoryBufferManager:
   std::unique_ptr<gfx::GpuMemoryBuffer> AllocateGpuMemoryBuffer(
       const gfx::Size& size,
       gfx::BufferFormat format,
       gfx::BufferUsage usage,
       gpu::SurfaceHandle surface_handle) override;
   std::unique_ptr<gfx::GpuMemoryBuffer> CreateGpuMemoryBufferFromHandle(
       const gfx::GpuMemoryBufferHandle& handle,
       const gfx::Size& size,
       gfx::BufferFormat format) override;
-  gfx::GpuMemoryBuffer* GpuMemoryBufferFromClientBuffer(
-      ClientBuffer buffer) override;
   void SetDestructionSyncToken(gfx::GpuMemoryBuffer* buffer,
                                const gpu::SyncToken& sync_token) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MojoGpuMemoryBufferManager);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_MUS_MOJO_GPU_MEMORY_BUFFER_MANAGER_H_