This issue was WONTFIX'd https://bugs.chromium.org/p/chromium/issues/detail?id=753646 because "Chrome stops the service worker after 5+ minutes timeout even if it is streaming."

This means it's impossible to use service worker to serve a stream of a 2hr movie.

I feels like we should enable this somehow. Eg fetchEvent.waitUntil should be able to keep the service worker alive for as long as the fetch is in-progress.