CommandBufferProxyImpl holds on to GpuMemoryBuffers while they are in use.

gpu/ipc/client/command_buffer_proxy_impl.h

Index: gpu/ipc/client/command_buffer_proxy_impl.h
diff --git a/gpu/ipc/client/command_buffer_proxy_impl.h b/gpu/ipc/client/command_buffer_proxy_impl.h
index aa47fe30122cd868f30da7916e2b74f374fd7add..757662bcec8674aaf1dd9e69995fbbf07c6f73d4 100644
--- a/gpu/ipc/client/command_buffer_proxy_impl.h
+++ b/gpu/ipc/client/command_buffer_proxy_impl.h
@@ -299,6 +299,11 @@ class GPU_EXPORT CommandBufferProxyImpl
   // A map from image id to GpuMemoryBuffer id.
   std::map<int32_t, int32_t> image_gmb_ids_map_;
 
+  // A map of GpuMemoryBuffers owned by this class (created from
+  // CreateGpuMemoryBufferImage). Unfortunatley, this cannot be combined with
+  // |image_gmb_ids_map_| since that container does not imply ownership.

[piman, 2016/06/06 19:28:52]

nit: would it be possible to combine both maps, by having a move-only struct
that has both the GMB id and the unique_ptr?
struct ImageInfo {
  int32_t gpu_memory_buffer_id;
  std::unique_ptr<gfx::GpuMemoryBuffer> owned_gpu_memory_buffer;
};

Otherwise, can you mention that the index is the image id as well (not clear
here).

[erikchen, 2016/06/06 21:55:54]

I created the ImageInfo struct as you suggested.

+  std::map<int32_t, std::unique_ptr<gfx::GpuMemoryBuffer>> image_gmb_map_;
+
   base::WeakPtr<CommandBufferProxyImpl> weak_this_;
   scoped_refptr<base::SequencedTaskRunner> callback_thread_;