function addGroupingOption(name, id)
        {
            var option = this._groupByCombobox.createOption(name, "", id);
            this._groupByCombobox.addOption(option);
            if (id === this._groupBySetting.get())
                this._groupByCombobox.select(option);
        }
@param {string} name
@param {string} id
@this {WebInspector.TimelineTreeView}