message: Only create steps_per_run_variable if it is tpu strategy.
diff: @@ -1241,6 +1241,7 @@ class Estimator(object):
  # We want to create the iterations variable outside the distribution scope
  # as that is just stored on the host and mainly used to drive the loop
  # and doesn't need to be a Mirrored/Device variable.
  + if is_tpu_strategy:
  steps_per_run_variable = training.get_or_create_steps_per_run_variable()
  with self._train_distribution.scope():
  random_seed.set_random_seed(self._config.tf_random_seed)
  