message: Make src_dir optional.
diff: @@ -22,6 +22,7 @@ import argparse
  import fnmatch
  import os
  import shutil
  +import tempfile
  import six
  @@ -544,9 +545,9 @@ class DocGenerator(object):
  self.argument_parser.add_argument(
  '--src_dir',
  type=str,
  - default=None,
  - required=True,
  - help='Directory with the source docs.')
  + default=tempfile.mkdtemp(),
  + required=False,
  + help='Optional directory of source docs to add api_docs links to')
  def add_base_dir_argument(self, default_base_dir):
  self.argument_parser.add_argument(
  