Use mus::MojoGpuMemoryBufferManager in mus::GpuService.

components/mus/gpu/gpu_service_impl.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 COMPONENTS_MUS_GPU_GPU_SERVICE_IMPL_H_
 #define COMPONENTS_MUS_GPU_GPU_SERVICE_IMPL_H_
 
 #include "components/mus/public/interfaces/gpu_memory_buffer.mojom.h"
 #include "components/mus/public/interfaces/gpu_service.mojom.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
@@ skipping 31 matching lines @@
       mojom::BufferFormat format,
       const mojom::GpuService::CreateGpuMemoryBufferFromHandleCallback&
           callback) override;
 
   void DestroyGpuMemoryBuffer(mojom::GpuMemoryBufferIdPtr id,
                               const gpu::SyncToken& sync_token) override;
 
  private:
   mojo::StrongBinding<GpuService> binding_;
 
-  // A unique client id for constructing the GpuChannel.
-  const int32_t client_id_;
-
   DISALLOW_COPY_AND_ASSIGN(GpuServiceImpl);
 };
 
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_GPU_GPU_SERVICE_IMPL_H_