GitLab

This CL moves RecommendationRestorer class to ash. The class exposes
an ObservePrefs method to let caller start observing recommended values
for a pref name.

TBR=bartfab@chromium.org

Bug: 839150
Test: covered by tests and enterprise-enrolled device test
Change-Id: I57b80c49ff8b0d5ab27102abf57b9a21b6b95c0a
Reviewed-on: https://chromium-review.googlesource.com/1023158
Commit-Queue: Qiang Xu <warx@google.com>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Gabriel Charette <gab@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#561591}