# File lib/new_relic/rack/browser_monitoring.rb, line 31
    def traced_call(env)
      result = @app.call(env)   # [status, headers, response]

      js_to_inject = NewRelic::Agent.browser_timing_header
      if (js_to_inject != "") && should_instrument?(env, result[0], result[1])
        response_string = autoinstrument_source(result[2], result[1], js_to_inject)

        env[ALREADY_INSTRUMENTED_KEY] = true
        if response_string
          response = Rack::Response.new(response_string, result[0], result[1])
          response.finish
        else
          result
        end
      else
        result
      end
    end