Merge "DO NOT MERGE Disallow Wallpaper service to launch activity from background." into tm-dev am: caf5747b97

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/23912846

Change-Id: Ide00acd65b62071719a92cf6ef06809d90b503c1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>