Revert "Replace field injection with constructor  injection." am: fb64691c44

Original change: https://android-review.googlesource.com/c/platform/packages/apps/ThemePicker/+/3344343

Change-Id: I229bff265a52846c1f6689e29146edac5595b5e9
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>