tree accaa8e3d087b75deb204ce7e1f62bcb689ab72c
parent c35416be8f2da25dbfcc90e10f801ce52e2f5833
author bohanli <bohanli@google.com> 1591917314 -0700
committer Bohan Li <bohanli@google.com> 1593662972 +0000

Save arf index in gf_group.

This removes hard-coded reference to the arf frame in gf group and
makes it easier to check whether arf is enabled in a gf group.

In the future if arf is not the second frame in a gf group, this also
avoids potential problems.

Change-Id: Ic723a651559191ba567078ad9ba0f22667e005a7