chromium/third_party/blink/web_tests/http/tests/priorities/resources/render-blocking-stylesheet.html

<script src="common.js"></script>
<script>
  observeAndReportResourceLoadPriority(new URL("../../resources/dummy.css?render-blocking", location));
</script>

<!-- Media-matching style sheets block rendering, and are critical -->
<link href="../../resources/dummy.css?render-blocking" rel="stylesheet" onload="reportLoaded()" onerror="reportFailure()">