alue: ''
      }

    },

    listeners: {
      'addon-attached': '_onAddonAttached'
    },

    observers: [
      '_focusedControlStateChanged(focused)'
    ],

    /**
     * Returns a reference to the input element.
     */
    get inputElement() {
      return this.$.input;
    },

    attached: function() {
      this._updateAriaLabelledBy();
    },

    _appendStringWithSpace: function(str, more) {
      if (str) {
        str = str + ' ' + more;
      } else {
        str = more;
      }
      retu