message: Add `batch_size` to allowed kwargs for backwards compatibility.
diff: @@ -1194,10 +1194,14 @@ class TensorBoard(Callback):
  if kwargs.get('embeddings_freq', False):
  logging.warning('Embeddings will be ignored in TensorFlow 2.0 '
  'for the `TensorBoard` Callback.')
  + if kwargs.get('batch_size', False):
  + logging.warning('`batch_size` is no longer needed in the '
  + '`TensorBoard` Callback and will be ignored '
  + 'in TensorFlow 2.0.')
  unrecognized_kwargs = set(kwargs.keys()) - {
  'write_grads', 'embeddings_freq', 'embeddings_layer_names',
  - 'embeddings_metadata', 'embeddings_data'
  + 'embeddings_metadata', 'embeddings_data', 'batch_size'
  }
  # Only allow kwargs that were supported in V1.
  