chromium/src/third_party/blink/web_tests/http/tests/inspector-protocol/resources/mixed-content-xhr.html

<script>
    // An insecure resource loaded using XMLHttpRequest
    var request = new XMLHttpRequest();
    request.open("GET", "http://devtools.test:8000/inspector-protocol/resources/request-data.js", true);
    request.send();
  </script>