chromium/third_party/blink/web_tests/external/wpt/workers/non-automated/navigator-onLine.js

if ('onmessage' in self) { // dedicated worker
  onmessage = function(e) {
    postMessage(navigator.onLine);
  }
} else { // shared worker
  onconnect = function(e) {
    e.ports[0].onmessage = function(e) {
      this.postMessage(navigator.onLine);
    }
  }
}