The `push` event in Service Workers currently doesn't have an explicit timeout assigned to it. This has led to some developers passing a never resolving promise to the event's waitUntil() method, which is undesirable.

The ServiceWorker.PushEvent.Time UMA shows that the 99th percentile is 23 seconds, 99.9th a minute, and 99.99th three minutes. We're hoping that this will decrease further as more developers adopt payloads.

We can match Background Sync's timeout of three minutes, or be more aggressive and go for one minute. In either case, we should fix  Issue 579137  to make sure that *a notification*, with or without images, can be shown within the timeout.