        return;
          }
          if (this._previousValue === undefined && value === '') {
            return;
          }
          this._previousValue = value;

          this._debouncerFilterChanged = Polymer.Debouncer.debounce(
            this._debouncerFilterChanged,
            Polymer.Async.timeOut.after(200),
            () => {
              this.dispatchEvent(new CustomEvent('filter-changed', {bubbles: true}));
            });
        }

        focus() {
          this.$.filter.focus();
    