constructor(browser, options) {
    super();
    this.browser_ = browser;
    this.options_ = options;
    this.windows_ = new Map();
    this.exposedFunctions_ = [];
    this.pendingWindows_ = new Map();
    this.windowSeq_ = 0;
    this.www_ = [];
  }
@param {!Puppeteer.Browser} browser Puppeteer browser
@param {!Object} options