Display tooltips in User Menu when the profile name is not editable.
This should fix the issue where no tooltip would be shown for long
supervised users' names.
BUG=482440
TEST=
1. Create a supervised user with a very long name
2. Open the User Menu by clicking on the Avatar Button
3. Hover over the profile name label
4. A tooltip displaying the full profile name should be shown
Note: No tooltip should be shown when the name is short enough to not
be elided in the User Menu.
Review URL: https://codereview.chromium.org/
1210153011
Cr-Commit-Position: refs/heads/master@{#337244}