[automerger skipped] [RESTRICT AUTOMERGE] Add hide-non-system-overlay flag for HarmfulAppWarningActivity am: 53ee9c24 am: be7090b0 -s ours am: b0cb54d5 -s ours am: 053326ec -s ours

am skip reason: subject contains skip directive

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/16743244

Change-Id: If5339b84ab84c556143f4ad637bd4fda61bf58e8