message: Clarify GpuDeviceInfo struct
diff: @@ -128,6 +128,8 @@ class DeviceBase {
  // using a single stream.)
  // "event_mgr" is used to delay deallocation of temporary GPU buffers.
  // TODO(pbar) Work out how to move this out of DeviceBase.
  + // GpuDeviceInfo name is an unfortunate legacy, it is used not only by GPUs
  + // but also by TPU devices (to provide default device context).
  struct GpuDeviceInfo {
  // Make sure all the defaults are NULL, so we can spot missing assignments.
  perftools::gputools::Stream* stream = nullptr;
  @@ -230,6 +232,7 @@ class DeviceBase {
  private:
  Env* const env_;
  CpuWorkerThreads* cpu_worker_threads_ = nullptr;
  + // Set by GPUs as well as by TPU devices.
  GpuDeviceInfo* gpu_device_info_ = nullptr;
  thread::ThreadPool* device_thread_pool_ = nullptr;
  Eigen::ThreadPoolDevice* eigen_cpu_device_ = nullptr;
  