message: Remove unused declaration.
diff: @@ -336,9 +336,6 @@ class PyLocalBuffer {
  std::shared_ptr<Literal> value;
  };
  - Status CopyToHostAsyncHelper(
  - se::Stream* stream, std::shared_ptr<HostValue> host_value,
  - std::shared_ptr<BufferDefinitionEvent> usage_event);
  StatusOr<std::pair<std::unique_ptr<PyLocalBuffer>,
  std::shared_ptr<BufferDefinitionEvent>>>
  CopyToDeviceHelper(Device* dst_device, LocalDeviceState* dst_local_device,
  