Merge "Implement Policy Listener add/remove in VcnService." am: 59035bd8c7 am: 3661eba6cc am: 0e6ac91cdc

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1532144

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Ia0a3fe3d29c52fc7fe349f7eb9af9899fbebbcee