Merge "Fixes activity leak in Wallpaper Picker." into udc-dev am: b7c4aec8b0 am: ff91a0d5a4

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/ThemePicker/+/23439007

Change-Id: Ic31cdfabbdfa72dc77419ab903865fc4dd3b21f9
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>