code: function () {
              // toggleDropdown should not make the virtual keyboard appear on touch devices
              this._updateFocusNoKeyboard(true);
              var report = this.controller.toggleDropdown(this.getTextInputField().value, this._dropdownPopup != null);
              this._reactToControllerReport(report, {
                  hasFocus : true
              });
          }
docs: Internal method called when the popup should be either closed or opened depending on the state of the
  controller and whether it is currently opened or closed. In any case, keep the focus on the field. Called by
  the widget button for example.
  @override