workbox: v3 bgSync replayRequests unsupported

Library Affected: workbox-backgroundSync

Browser & Platform: Google Chrome v63.0.3

I’m trying to set up background sync with Workbox v3. After #1222, I have basic functionality, and I’ve added the queueDidReplay callback to show a notification when bg sync occurs:

const showNotification = () => {
  self.registration.showNotification('Background sync success!', {
    body: '🎉`🎉`🎉`'
  });
};

const bgSyncPlugin = new workbox.backgroundSync.Plugin(
  'dashboardr-queue',
  {
    callbacks: {
      queueDidReplay: showNotification
    }
  }
);

const networkWithBackgroundSync = new workbox.strategies.NetworkOnly({
  plugins: [bgSyncPlugin],
});

const addEventRoute = new workbox.routing.Route(
  ({url}) => url.pathname === '/api/add',
  networkWithBackgroundSync,
  'POST'
);

workbox.routing.registerRoute(addEventRoute);

This currently works, but bg sync takes about 5 minutes to happen in Chrome, and I’d like to replay the queued requests immediately. To achieve this I tried calling

bgSyncPlugin.replayRequests()

But this doesn’t appear to work, as replayRequests is not a method of backgroundSync.Plugin:

Uncaught (in promise) TypeError: bgSyncPlugin.replayRequests is not a function
    at Object.replayAndReturn [as handle] (sw.js:110)
    at DefaultRouter.handleRequest (workbox-routing.dev.js:365)
    at workbox.routing.self.addEventListener.event (workbox-routing.dev.js:817)

So I changed backgroundSync.Plugin to backgroundsync.Queue, and that allows me to call replayRequests. But after switching to backgroundsync.Queue, failed requests are no longer being queued, and I’m not getting any console errors to indicate what’s going wrong.

I understand that I might not be able to just swap Plugin & Queue interchangably, but if using Queue is not that solution, then how would I implement this functionality with Plugin? If Queue is the answer, what am I doing wrong?

Separate but related issues: #1247 & #1249