get position() {
    return {
      x: this.window_.pageXOffset,
      y: this.window_.pageYOffset - this.topToolbarHeight_
    };
  }
/**
   * @type {Object} the scroll position of the viewport.
   */
@type {Object} the scroll position of the viewport.
@type { Object } the scroll position of the viewport .
get position() {
    return {
      x: this.window_.pageXOffset,
      y: this.window_.pageYOffset - this.topToolbarHeight_
    };
  }
get position ( ) { return { x : this . window_ . pageXOffset , y : this . window_ . pageYOffset - this . topToolbarHeight_ } ; }
@type {Object} the scroll position of the viewport.
@type { Object } the scroll position of the viewport .