Merge ChromeOSAddSupervision flag into ChromeOSParentalControlsSettings

Also added to enable-parental-controls-settings to chrome://flags

Bug: 927957
Change-Id: Ie720ee20b5c601514d312831fd03b582667acebc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1669890
Commit-Queue: Danan S <danan@chromium.org>
Reviewed-by: Michael Giuffrida <michaelpg@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#672305}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 749399c975fb2c1f9869d94ecd91b43aadd98f38
1 file changed