.
      let url = 'resources/resource_timing_test0.js?unique=' +
        Math.random().toString().substr(2);
      let frame;
      return add_iframe('resources/iframe-load-from-mem-cache-transfer-size.html')
        .then((f) => {
          frame = f;
          // Load script onto iframe in order to get it into the memory cache.
          return frame.contentWindow.getScript(url.split('/')[1])
        })
        .then(() => {
          // Verify that the transferSize in case of normal load is greater than
