fake_responses.html | Explore in Territory

<body>
<script>
function request(type) {
  var client = new XMLHttpRequest,
    identifier = type == "tag" ? Math.random() : new Date().toGMTString(),
    url = "fake_responses.py?" + type + "=" + identifier
    client.open("GET", url, false)
    client.send(null)
    client.open("GET", url, false)
    client.setRequestHeader(type == "tag" ? "If-None-Match" : "If-Modified-Since", identifier)
    client.send(null)
}

if(window.parent.setup_iframe) {
  window.parent.setup_iframe();
  request("tag");
}
</script>
</body>

chromium/third_party/blink/web_tests/external/wpt/resource-timing/resources/fake_responses.html