GetAvatarForIdentity now accepts a nil callback function.

Change-Id: I6dedc52a8f0eb4ff4bd0186158485bd15671e89e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1618316
Auto-Submit: Peter Lee <pkl@chromium.org>
Commit-Queue: Jérôme Lebel <jlebel@chromium.org>
Reviewed-by: Jérôme Lebel <jlebel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#661309}
2 files changed