For settings which can change in the framework, outside of
the settings app and a slice, a Slice needs to be able to
register a listener for these changes.
Adding a getter for an IntentFilter in BasePreferenceControllers
allows us to use the SliceBroadcastRelay in SysUi to listen for
these changes.
Test: robotests
Fixes: 78138654
Change-Id: I579375069ca98fd21b60cd3a69c1a122cabf96e2
Merged-In: Ifa05b651aaa3458c54866f71469964b1a070e458
4a6f058552