# File lib/jquery/fileupload/rails/middleware.rb, line 13
        def _call(env)
          @status, @headers, @response = @app.call(env)
          @request = Rack::Request.new(env)

          if iframe_transport?
            @headers['Content-Type'] = 'text/html'
            [@status, @headers, self]
          else
            [@status, @headers, @response]
          end
        end