Add user to reviewers if they click commit checkbox.
Add user to reviewers if they click commit checkbox.

BUG=225395
Review URL: https://chromiumcodereview.appspot.com/15231007/

nicko96/Chrome-Infra,nicko96/Chrome-Infra,nicko96/Chrome-Infra,nicko96/Chrome-Infra,nicko96/Chrome-Infra