Merge "Partially revert the usage of string enum." into udc-qpr-dev am: 26ad9a3a am: 47d0d9da

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/23997544



Change-Id: I6c224f2247c1d9031f64d59ced95325cbc0c6d9a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>