Add new broadcasts ACTION_MEDIA_RESOURCES_AVAILABLE and
ACTION_MEDIA_RESOURCES_UNAVAILABLE that get broadcast by
PackageManagerService when sdcard gets mounted/unmounted
by MountService so that packages on sdcard get recognized by
various system services as being installed/available or
removed/unavailable by the system.
The broadcasts are sent before the actual package cleanup which includes
mounting/unmounting the packages and we force a gc right after so
that any lingering file references to resources on sdcard get
released.
can happen if services are going away as the AccessibilityManagerService
is trying to dispatch notifications to these services. Catching this
exception and bailing because having this exception means that there
are no more services around that need to get this notification.