getSignInFlow() {
    const signInFlow = this.config_.get('signInFlow');
    // Make sure the select flow is a valid one.
    for (let key in Config.SignInFlow) {
      if (Config.SignInFlow[key] == signInFlow) {
        // Return valid flow.
        return Config.SignInFlow[key];
      }
    }
    // Default to redirect flow.
    return Config.SignInFlow.REDIRECT;
  }
@return {!Config.SignInFlow} The current sign-in flow.