Merge "Keep wallpaper as a special-case in transitions" into sc-v2-dev am:...

Merge "Keep wallpaper as a special-case in transitions" into sc-v2-dev am: ba34886c am: fc373c42

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15068561

Change-Id: Id2d5c5be38420fcb6c4c2ea69e73a7edf3712940