GitLab

Add an EnabledStateMonitor to monitor changes to contextualsuggestions
enabled state. Currently the only monitored state is whether sync
upload to Google is active.

Also updates the FeatureUtilities check to account for the search engine
promo.

BUG=823987

Change-Id: I9b4ae44ae94e73ef5c7e43cbfe6aebf657f4ada0
Reviewed-on: https://chromium-review.googlesource.com/988343Reviewed-by: Pavel Yatsuk <pavely@chromium.org>
Reviewed-by: Filip Gorski <fgorski@chromium.org>
Reviewed-by: Tommy Nyquist <nyquist@chromium.org>
Commit-Queue: Theresa <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548051}