Moves common screen preview logic to WPP2 (2/2). am: b169b2c1ea

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/ThemePicker/+/20815776

Change-Id: I9b6168ccf282ff5605f5cba2ec4fbc91b5d0b374
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>