# File lib/googleauth/web_user_authorizer.rb, line 159
      def get_authorization_url options = {}
        options = options.dup
        request = options[:request]
        raise NIL_REQUEST_ERROR if request.nil?
        raise NIL_SESSION_ERROR if request.session.nil?

        redirect_to = options[:redirect_to] || request.url
        request.session[XSRF_KEY] = SecureRandom.base64
        options[:state] = MultiJson.dump(
          SESSION_ID_KEY  => request.session[XSRF_KEY],
          CURRENT_URI_KEY => redirect_to
        )
        options[:base_url] = request.url
        super options
      end