GitLab

Cause:
The crash opt-in setting is sometimes controlled by domain policy, which will
prevent the user from enabling it.  However, this is not communicated to the
user properly.

Fix:
- Shows a tooltip "This setting is controlled by your domain policy" if
  necessary.
- Hides the check box if the domain doesn't allow usage stats collection
  as an empty disabled check box offers no value to the user.

BUG=388864

Review URL: https://codereview.chromium.org/898163002

Cr-Commit-Position: refs/heads/master@{#315105}