getPrivacyPolicyUrl() {
    const tosUrl = this.config_.get('tosUrl') || null;
    const privacyPolicyUrl = this.config_.get('privacyPolicyUrl') || null;
    if (privacyPolicyUrl && !tosUrl) {
      log.warning(
          'Terms of Service URL is missing, the link will not be displayed.');
    }
    if (tosUrl && privacyPolicyUrl) {
      if (typeof privacyPolicyUrl === 'function') {
          return /** @type {function()} */ (privacyPolicyUrl);
      } else if (typeof privacyPolicyUrl === 'string') {
        return () => {
          util.open(
              /** @type {string} */ (privacyPolicyUrl),
              util.isCordovaInAppBrowserInstalled() ?
              '_system' : '_blank');
        };
      }
    }
    return null;
  }
Returns the privacy policy callback. Returns null if either terms of
service or privacy policy is not configured.
@return {?function()} The privacy policy callback for the tenant selection
    UI. If URL is provided, wraps the URL with a callback function.