Merge "Adds listener support to FakeFeatureFlags" into tm-qpr-dev am: 34fdbdb544 am: eb40375d6c

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/19763934

Change-Id: Ief57092ca3366a450850913437587669d56c8977
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>