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

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

Change-Id: Ifa761835d3719a24206b83d69f214f2e70cf4237
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>