Method constructor

src/service/performance-impl.js:102–287

* @param {!Window} win

(win)

   * @param {!Window} win
   */
  constructor(win) {
    /** @const {!Window} */
    this.win = win;

    /** @const {string} */
    this.eventid_ = base64UrlEncodeFromBytes(
      getCryptoRandomBytesArray(win, 16)
    );

    /** @const @private {!Array<TickEventDef>} */
    this.events_ = [];

    /** @const @private {number} */
    this.timeOrigin_ =
      win.performance.timeOrigin || win.performance.timing.navigationStart;

    /** @private {?./ampdoc-impl.AmpDoc} */
    this.ampdoc_ = null;

    /** @private {?./viewer-interface.ViewerInterface} */
    this.viewer_ = null;

    /** @private {?./resources-interface.ResourcesInterface} */
    this.resources_ = null;

    /** @private {?./document-info-impl.DocumentInfoDef} */
    this.documentInfo_ = null;

    /** @private {boolean} */
    this.isMessagingReady_ = false;

    /** @private {boolean} */
    this.isPerformanceTrackingOn_ = false;

    /** @private {!{[key: string]: boolean}} */
    this.enabledExperiments_ = map();

    /** @private {string|undefined} */
    this.ampexp_ = undefined;

    /** @private {Signals} */
    this.metrics_ = new Signals();

    /**
     * How many times a layout shift metric has been ticked.
     *
     * @private {number}
     */
    this.shiftScoresTicked_ = 0;

    /**
     * The collection of layout shift events from the Layout Instability API,
     * used for normalized windowed sessions according to the latest CWV
     * implementation. This uses 5s max window with a 1s session gap as the
     * session size.
     * See https://github.com/GoogleChrome/web-vitals/blob/main/src/getCLS.ts
     * @private {Array<LayoutShift>}
     */