message: Introduce ShutdownTpuSystem op.
diff: @@ -1508,6 +1508,17 @@ InitializeHostForDistributedTpuOp, and outputs the latter's result.
  );
  }
  +def TF_ShutdownTPUSystemOp : TF_Op<"ShutdownTPUSystem", []> {
  + let summary = [{
  +An op that shuts down the TPU system.
  + }];
  +
  + let arguments = (ins);
  + let results = (outs
  + TF_BoolTensor:$success
  + );
  +}
  +
  // Internal op for testing value-based side-effects for non-resource values.
  // TODO(mgester) We should have an extension of TF dialect only for testing so
  // TF dialect is not polluted with test ops.
  