ref: a6874985e2e7449a85cc0ad04930e41169e961e4
parent: 03abd2c8f358549a445dce452e26aa72d3853e55
author: Zoe Liu <zoeliu@google.com>
date: Fri Jun 22 15:33:38 EDT 2018
Add hierarchical structure based ref frame update Change-Id: I23559110bae8fa2328fe9bdb6672c7b1da84e17f