request subscription browser

push-upload-browser.ts

navigator.serviceWorker.ready.then(serviceWorkerRegistration => {
  const options = {userVisibleOnly: true, applicationServerKey: applicationServerKey};
  serviceWorkerRegistration.pushManager.subscribe(options).then(pushSubscription => {
    navigator.serviceWorker.controller.postMessage({
      action: 'REQUEST_SUBSCRIPTION',
      subscription: pushSubscription
    });
    uploadSubscriptionToTheServer(pushSubscription, userId);
  });
});