def gen_file_header(prog_name, meta_name):
  """Returns the header for the generated expiry list file.

  The generated header contains at least:
  * A copyright message on the first line
  * A reference to this program (prog_name)
  * A reference to the input metadata file
  >>> 'The Chromium Authors' in gen_file_header('foo', 'bar')
  True
  >>> '/progname' in gen_file_header('/progname', '/dataname')
  True
  >>> '/dataname' in gen_file_header('/progname', '/dataname')
  True
  """
  return """// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This is a generated file. Do not edit it! It was generated by:
//   {prog_name}
// and it was generated from:
//   {meta_name}

#include "chrome/browser/expired_flags_list.h"

namespace flags {{
const ExpiredFlag kExpiredFlags[] = {{
""".format(prog_name=prog_name, meta_name=meta_name)