Read JSON-formatted proto into DatasetInfo proto.

def read_from_json(json_filename):
  """Read JSON-formatted proto into DatasetInfo proto."""
  with tf.io.gfile.GFile(json_filename) as f:
    dataset_info_json_str = f.read()
  # Parse it back into a proto.
  parsed_proto = json_format.Parse(dataset_info_json_str,
                                   dataset_info_pb2.DatasetInfo())
  return parsed_proto