Merge "Update wallpaper window pages only at processing" into sc-v2-dev am: 4c79fd90 am: 85a1a024

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/16365763

Change-Id: Ib3febe6cb2697cde6490d595c5e99a2b6e2fc987