[automerger skipped] Add RootTargetPreparer for explicitly specifying the root dependency am: 3c4f5273ea am: 821d9cdad6 -s ours

am skip reason: Merged-In I9b34a85025a6aa4f138483202fd11db0cbb8b04b with SHA-1 7c829f1edc is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/26764622

Change-Id: I0109316cc7b7372ea2ac6161249e090d48b3578f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>