As far as my code reading shows, if S13nSW/NetworkService is on, the "5 minute" event timeout happens in both the browser and renderer:

1. ServiceWorkerVersion's timeout timer
2. ServiceWorkerTimeoutTimer

The error codes are different on timeout. SWV will give the client a TIMEOUT while timeout timer gives an ABORT.

I tend to think TIMEOUT is better but we can revisit that separately.

We should at least have a consistent error code and avoid complexity. Probably we can  skip request expiration on the browser process. It's a bit scary because it means if there's a bug somehow that causes the renderer to not timeout the event, we will never terminate the service worker. We could potentially keep some big hammer, last resort mechanism on the browser (something like if an event's been running 10 minutes, just terminate). Not sure it's worth it though.

Doesn't block canary.