Merge "Prevent crash if detachWallpaperLocked is called multiple times" into udc-dev am: 0786743a am: 752c0661

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/21651263



Change-Id: I2508d9bafbfaec1dbfad9df4dc081ff1da348fc6
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>