'Infers user name and subject urn from self.urn.'

def InferUserAndSubjectFromUrn(self):

    (_, cron_str, cron_job_name, user, _) = self.urn.Split(5)
    if (cron_str != 'cron'):
        raise access_control.UnauthorizedAccess(('Approval    object    has    invalid    urn    %s.' % self.urn), requested_access=self.token.requested_access)
    return (user, aff4.ROOT_URN.Add('cron').Add(cron_job_name))
