[automerger skipped] DO NOT MERGE: Fix ActivityManager#killBackgroundProcesses permissions am: 9a14267036 -s ours am: c2318438d7 -s ours

am skip reason: subject contains skip directive

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/25124582

Change-Id: I66c716847338aecf7154ecac9db2f59d064e0304
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>