chromium/content/test/data/service_worker/throttling_blocking_sw.js

// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

self.addEventListener('install', evt => {
  evt.waitUntil(async function() {
    return Promise.all([
      fetch('./foo/1?block').then(r => r.blob()),
      fetch('./foo/2?block').then(r => r.blob()),
      fetch('./foo/3?block').then(r => r.blob()),
    ]);
  }());
});