[automerger skipped] Add RootTargetPreparer for explicitly specifying the root dependency am: 58077070ec am: 61dfa97c9c -s ours am: 03b40df635 -s ours am: 30e5662b92 -s ours

am skip reason: Merged-In I9b34a85025a6aa4f138483202fd11db0cbb8b04b with SHA-1 3c4f5273ea is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/26928402

Change-Id: I937f98660f326e9127e1f89752708244db877c24
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>