Add bit accounting information for deringing

It seems that when bit accounting was introduced in
https://chromium-review.googlesource.com/#/c/400658/
there was one place which was accidentally skipped, leading to build failures
with --enable-dering. This patch adds the missing information.

Change-Id: I59e1bd6f7e1d4fa58506ee7af307b845c78a7cbe