Finish a few MDB TODOs

Change-Id: I5579bea381ce30dc59502dbeb5841fea927002c2
Reviewed-on: https://skia-review.googlesource.com/20640
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
4 files changed