If users click to pair a not foundable device and then close the Settings page,
Settings will crash becasue dialog holder is closed.
This CL is part of the fix. It set the context to null when the activity
stops.
Bug: 306548036
Test: atest
Change-Id: If68e3e9cd62216ad83b2e5058f504fce35e36a06
The section only show at most 3 devices. If the device list size is
greater than 3, we will show a "See all".
The device Preference is ordered. FastPairDeviceUpdater will handle the
order logic.
Bug: 296507968
Test: FastPairDevicePreferenceControllerTest
Change-Id: I9692d5740dbc31ff50db0ebbf2c5535b726277c9
