Add nullability annotations for those missing.

Change-Id: Ie37a6821890db0b8e252ed064642857f4a94ab0e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1677844
Auto-Submit: Hiroshi Ichikawa <ichikawa@chromium.org>
Reviewed-by: John Wu <jzw@chromium.org>
Commit-Queue: Hiroshi Ichikawa <ichikawa@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672712}
5 files changed