def GetBuildShortBaseName(target_platform):
  """Returns the build base directory.

  Args:
    target_platform: Target platform.
  Returns:
    Build base directory.
  Raises:
    RuntimeError: if target_platform is not supported.
  """

  platform_dict = {
      'Windows': 'out_win',
      'Mac': 'out_mac',
      'Linux': 'out_linux',
      'Android': 'out_android',
      'NaCl': 'out_nacl'
  }

  if target_platform not in platform_dict:
    raise RuntimeError('Unkown target_platform: ' + (target_platform or 'None'))

  return platform_dict[target_platform]