message: Include `call_once.h` in `tpu_functional_ops.h`
diff: @@ -16,6 +16,7 @@ limitations under the License.
  #ifndef TENSORFLOW_CORE_TPU_KERNELS_TPU_FUNCTIONAL_OPS_H_
  #define TENSORFLOW_CORE_TPU_KERNELS_TPU_FUNCTIONAL_OPS_H_
  +#include "absl/base/call_once.h"
  #include "tensorflow/compiler/jit/shape_inference.h"
  #include "tensorflow/core/common_runtime/device_mgr.h"
  #include "tensorflow/core/common_runtime/optimization_registry.h"
  