Revert "Revert "Replace field injection with constructor  inject..." am: c00c07f112

Original change: https://android-review.googlesource.com/c/platform/packages/apps/ThemePicker/+/3340780

Change-Id: I685e3e5256b7c221381133486054ff582936d361
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>