Merge "Remove possible residual callbacks when detach wallpaper." into rvc-qpr-dev am: 4d7f81e979 am: 66eea5dbdd

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/12202963

Change-Id: I96391e78f990be3e51869b8caa5d19884ca3e6ab