static function _store_basename_for_source_adjustment( $response, $hook_extra ) {
            if ( isset( $hook_extra['plugin'] ) ) {
                self::$_upgrade_basename = $hook_extra['plugin'];
            } else if ( isset( $hook_extra['theme'] ) ) {
                self::$_upgrade_basename = $hook_extra['theme'];
            } else {
                self::$_upgrade_basename = null;
            }

            return $response;
        }