This change extracts some utility code from AnnouncementsService.java and AnnouncementsBroadcastService.java into a BackgroundService superclass. The idea is that other Android services will extend BackgroundService.
Change wasn't landed with fennec-copy-code.sh, so it's missing makefile entries.
I will reland when tree reopens. Chris: in future, you need to run something like: cd ~/moz/hg/mozilla-inbound hg qnew -m "..." cd ~/moz/git/android-sync ./fennec-copy-code.sh ~/moz/hg/mozilla-inbound cd - hg add ... hg qref
Relanded with manifest changes: https://hg.mozilla.org/integration/mozilla-inbound/rev/74d4c4a7e5c0