GitLab

The user avatar did not have proper tooltip when it's guest session.

TEST=manual
BUG=889831

Change-Id: I620704000b2d01b83406eeebc301c54a4138bac1
Reviewed-on: https://chromium-review.googlesource.com/1250383Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
Commit-Queue: Tetsui Ohkubo <tetsui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595470}