This adds two guards, first checking when the provider
list is generated to stop and flag an warning, second
to have PackageMonitor use a handler so callbacks should
only happen on the thread that the fragment is running
on and if that is no longer available it won't do
anything.
Test: ondevice
Bug: 296164461
Change-Id: Iab03f8a10e667694e2e23da7574831f9ea5c38e2
dc5e10e3cc