text: /**
   * Public options for the PageVisibilityTracker.
   * @typedef {{
   *   sessionTimeout: (number),
   *   visibleThreshold: (number),
   *   timeZone: (string|undefined),
   *   visibleMetricIndex: (number|undefined),
   *   fieldsObj: (!Object),
   *   hitFilter: (Function|undefined),
   * }}
   */
  var PageVisibilityTrackerOpts;
  
  
  /**
   * PageVisibilityTracker change store data schema.
   * @typedef {{
   *   time: (number|undefined),
   *   state: (string|undefined),
   *   pageId: (string|undefined),
   * }}
   */
  var PageVisibilityStoreData;
  
  
  /**
   * @interface
   */
  class PageVisibilityTrackerPublicInterface {
    remove() {}
  }
  