Convert Label fields to be properties

Bug: 972742
Change-Id: I5f17dcf6aea9a6182a30e844a1003ffce7d0c020
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1647357
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Allen Bauer <kylixrd@chromium.org>
Commit-Queue: Kristyn Hamasaki <khamasaki@google.com>
Cr-Commit-Position: refs/heads/master@{#672257}
77 files changed