gpu: Directly cast ClientBuffer to gfx::GpuMemoryBuffer

ui/aura/mus/mojo_gpu_memory_buffer_manager.cc

 // 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.
 
 #include "ui/aura/mus/mojo_gpu_memory_buffer_manager.h"
 
 #include "base/logging.h"
 #include "ui/aura/mus/mojo_gpu_memory_buffer.h"
 
 namespace aura {
@@ skipping 13 matching lines @@
 
 std::unique_ptr<gfx::GpuMemoryBuffer>
 MojoGpuMemoryBufferManager::CreateGpuMemoryBufferFromHandle(
     const gfx::GpuMemoryBufferHandle& handle,
     const gfx::Size& size,
     gfx::BufferFormat format) {
   const gfx::BufferUsage usage = gfx::BufferUsage::GPU_READ;
   return MojoGpuMemoryBufferImpl::CreateFromHandle(handle, size, format, usage);
 }
 
-gfx::GpuMemoryBuffer*
-MojoGpuMemoryBufferManager::GpuMemoryBufferFromClientBuffer(
-    ClientBuffer buffer) {
-  return MojoGpuMemoryBufferImpl::FromClientBuffer(buffer);
-}
-
 void MojoGpuMemoryBufferManager::SetDestructionSyncToken(
     gfx::GpuMemoryBuffer* buffer,
     const gpu::SyncToken& sync_token) {
   NOTIMPLEMENTED();
 }
 
 }  // namespace aura