chromium/third_party/blink/web_tests/external/wpt/service-workers/service-worker/resources/websocket.js

self.urls = [];
self.addEventListener('fetch', function(event) {
    self.urls.push(event.request.url);
  });
self.addEventListener('message', function(event) {
    event.data.port.postMessage({urls: self.urls});
  });