Merge "Add a way to reset persistent letterbox positions." into udc-qpr-dev am: e8c4f268ab am: 2c6b9c6089

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/24526911

Change-Id: Id4a23095cc425f0606e0d1b3b06c33d5b832b3df
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>