Taking this

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/17d11907ccd0ed818d2a9f6d0db145dfea03871f

commit 17d11907ccd0ed818d2a9f6d0db145dfea03871f
Author: Sergio Villar Senin <svillar@igalia.com>
Date: Tue Oct 16 09:04:27 2018

Convert arc_terms_of_service_screen_handler.cc to IdentityManager

It was using SigninManagerBase API to get the primary (authenticated)
account id. It's now using the IdentityManager API.

Bug:  890808 
Change-Id: Ifabe11ca68de07949fcad2f81c022723dcb842ef
Reviewed-on: https://chromium-review.googlesource.com/c/1276769
Reviewed-by: Colin Blundell <blundell@chromium.org>
Reviewed-by: Alexander Alekseev <alemate@chromium.org>
Commit-Queue: Sergio Villar <svillar@igalia.com>
Cr-Commit-Position: refs/heads/master@{#599925}
[modify] https://crrev.com/17d11907ccd0ed818d2a9f6d0db145dfea03871f/chrome/browser/ui/webui/chromeos/login/arc_terms_of_service_screen_handler.cc

Fixed!