cancel() {
    // Call underlying googleyolo API if supported and previously initialized.
    // If googleyolo is not yet loaded, there is no need to run cancel even
    // after loading since there is nothing to cancel.
    if (this.googleyolo_ && this.initialized_) {
      if (this.callback_) {
        this.callback_(null);
      }
      this.googleyolo_.cancel();
    }
  }
Cancels any pending One-Tap operation if available.