Let me take over this bug.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/fac5b1f2211b8323d145dc8cfbddc9594dc9fbaf

commit fac5b1f2211b8323d145dc8cfbddc9594dc9fbaf
Author: Gyuyoung Kim <gyuyoung@igalia.com>
Date: Thu Jan 17 01:12:48 2019

s13n: Remove SigninManager-related includes from app_controller_mac.mm and its unittest

Clean up sign-in-related code in app_controller_mac.mm and app_controller_mac_unittest.mm
because there are no uses of SigninManager.

Bug:  920201 
Change-Id: I0466c2ccea572af4f60cc1fbbd7b5584bd2b586c
Reviewed-on: https://chromium-review.googlesource.com/c/1414211
Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Gyuyoung Kim <gyuyoung@igalia.com>
Cr-Commit-Position: refs/heads/master@{#623491}
[modify] https://crrev.com/fac5b1f2211b8323d145dc8cfbddc9594dc9fbaf/chrome/browser/app_controller_mac.mm
[modify] https://crrev.com/fac5b1f2211b8323d145dc8cfbddc9594dc9fbaf/chrome/browser/app_controller_mac_unittest.mm