Chrome OS: Integrate Discover PIN setup into First run UI.

TBR=alemate@chromium.org

(cherry picked from commit 761a7e81af6dfcf0e5e1c29721d9a9c73a3dd19a)

Bug: 852553
Change-Id: I215392305eee1555441d5dd66f0bb2908d0f5525
Reviewed-on: https://chromium-review.googlesource.com/c/1250136
Commit-Queue: Alexander Alekseev <alemate@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#599137}
Reviewed-on: https://chromium-review.googlesource.com/c/1293181
Reviewed-by: Alexander Alekseev <alemate@chromium.org>
Cr-Commit-Position: refs/branch-heads/3578@{#198}
Cr-Branched-From: 4226ddf99103e493d7afb23a4c7902ee496108b6-refs/heads/master@{#599034}
9 files changed