Implement GetRootOfTrust am: 18cf62712c am: 8b6990afb2

Original change: https://googleplex-android-review.googlesource.com/c/platform/system/core/+/18868385

Change-Id: Ic8422dce80373ec297c511955e2fe5832ca57d6c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>