Merge "Fullscreen image preview (Part 3)" into ub-launcher3-master am: d09b0ad1cc am: fca2c86a04

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/WallpaperPicker2/+/11444577

Change-Id: I71306a12ebbce3ae42ff9c74c1b430ca101da175