constructor(injectedDataSupplier = undefined, domHelper = undefined) {
    /** @private @const {!dom.DomHelper} */
    this.dom_ = domHelper || dom.getDomHelper();

    /** @private @const {?InjectedDataSupplier} */
    this.supplier_ = injectedDataSupplier || null;
  }
@param {?InjectedDataSupplier=} injectedDataSupplier A supplier that
    provides an injected data.
@param {?dom.DomHelper=} domHelper Optional DOM helper; defaults to that
    provided by `dom.getDomHelper()`.