Add notifications when time limit policy is updated

Bug: 936938
Change-Id: I28f446f9edcb5a719855a87f65f2a0543d4ee88f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1572703
Commit-Queue: Henrique Grandinetti <hgrandinetti@chromium.org>
Reviewed-by: Michael Giuffrida <michaelpg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#654018}
12 files changed