     /**
         * When the dropdown opens, the `paper-menu-button` fires `paper-open`.
         * When the dropdown closes, the `paper-menu-button` fires `paper-close`.
         *
         * @param {boolean} opened True if the dropdown is opened, otherwise false.
         * @param {boolean} oldOpened The previous value of `opened`.
         */
        _openedChanged: function(opened, oldOpened) {
          if (opened) {
            // TODO(cdata): Update this when we can measure changes in distributed
   