private function store_file_slug_map() {
            $file_slug_map = self::$_accounts->get_option( 'file_slug_map', array() );

            if ( ! array( $file_slug_map ) ) {
                $file_slug_map = array();
            }

            if ( ! isset( $file_slug_map[ $this->_plugin_basename ] ) ||
                 $file_slug_map[ $this->_plugin_basename ] !== $this->_slug
            ) {
                $file_slug_map[ $this->_plugin_basename ] = $this->_slug;
                self::$_accounts->set_option( 'file_slug_map', $file_slug_map, true );
            }
        }