When an update timer fires, we first check browser.safebrowsing.provider.*.nextupdatetime to decide whether or not to download the new list from the server. If the time has not passed yet, then we set a new timer 30 minutes later (?). We could however run into the following problem: 1. update the Google lists at 12:00, next update scheduled for 12:30 2. restart the browser at 12:29 3. update is skipped because the current time is less than nextupdatetime, next update scheduled for 12:59 4. list goes stale at 12:45 and will be stale until 12:59 Instead of setting a new timer for 30 minutes later when the nextupdatetime fails, we should set a timer for "nextupdatetime + 5 min". We already do something similar for backoff.
Dimi checked and this is not going to happen. We already guard against that.