In bug 1238087 we implemented content notifications with the following logic for subscribing/unsubscribing: After device reboot or app start: Reset timers and set the following new timers: * After 15 minutes check for websites that we should not be subscribed to anymore. Then repeat every day. * After 30 minutes check for new websites that we can subscribe to. Then repeat every day. -> The list of subscriptions is updated once a day. It might happen more often if the app is started more often (cold app start) because we reset the timers.

Also see bug 1248901: The JobScheduler API would allow us to use something more sensible like "Run this every X but only if you have a WiFi connection; Otherwise wait for WiFi to be available. And if this fails then retry after Y."

Content notification code was removed in bug 1396604.