update(account, opt_config) {
    if (typeof this.config_['callbacks']['update'] === 'function') {
      this.config_['callbacks']['update'](
          undefined, firebaseui.auth.acClient.DummyApi.UNAVAILABLE_ERROR_);
    }
  }
Updates the account. The callback is always invoked with a service
unavailable error.

@param {Object} account The account to update.
@param {Object=} opt_config The optional client configuration.