gpu: Directly cast ClientBuffer to gfx::GpuMemoryBuffer

blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.h

Index: blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.h
diff --git a/blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.h b/blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.h
index 794d781cbdd42cc4aff7eaaf52b50c6d75ca2562..e0501af492032984b3dfc7751364f5184ae25963 100644
--- a/blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.h
+++ b/blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.h
@@ -31,8 +31,6 @@ class BlimpGpuMemoryBufferManager : public gpu::GpuMemoryBufferManager {
       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;