chromium/third_party/blink/perf_tests/service_worker/hot-fetch.html

<!DOCTYPE html>
<html>
<head>
<script src='../resources/runner.js'></script>
</head>
<body>
<script>
let isDone = false;
function testDone() {
  isDone = true;
}

function addIframe(url) {
  return new Promise((resolve) => {
    var frame = document.createElement('iframe');
    frame.src = url;
    frame.onload = () => { resolve(frame); };
    document.body.appendChild(frame);
  });
}

function waitForWorkerActive(worker) {
  return new Promise((resolve) => {
    worker.addEventListener('statechange', () => {
      if (worker.state == 'activated')
        resolve();
    });
  });
}

async function runTest() {
  const script = '/service_worker/resources/fetch-service-worker.js';
  const scope = '/service_worker/resources/';
  const client = '/service_worker/resources/simple.html';
  const resource = '/service_worker/resources/data/1K_0.txt';

  const registration = await navigator.serviceWorker.register(
      script, { scope: scope });
  await waitForWorkerActive(registration.installing);
  const frame = await addIframe(client);

  while (!isDone) {
    const startTime = performance.now();
    const response = await frame.contentWindow.fetch(resource);
    PerfTestRunner.measureValueAsync(performance.now() - startTime);
  }
  return;
}

PerfTestRunner.startMeasureValuesAsync({
  description: 'Measure the performance of fetch with live service worker.',
  unit: 'ms',
  run: runTest,
  done: testDone,
  iterationCount: 30
});
</script>
</body>
</html>