Make custom theme remeber selections while system config changes and then...

Make custom theme remeber selections while system config changes and then restore am: e6c8fa86 am: 376fb455

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/ThemePicker/+/11630518

Change-Id: I84b8cfe8b62c76a5e6f228bbe20b9a07d34cf2f6