"API replacement summary:
- AccountTrackerService::Observer::OnAccountUpdated => IdentityManager::Observer::OnAccountUpdated
- AccountTrackerService::FindAccountInfoByEmail => IdentityManager::FindAccountInfoForAccountWithRefreshTokenByEmailAddress
- AccountTrackerService::SeedAccountInfo => IdentityTestEnvironment or identity_test_utils to make account available
- AccountTrackerService::RemoveAccount => AccountsMutator::RemoveAccount
"

Let me take over this bug.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b9a3a6e9fc748ced98a6479cbbeffffe1e5edbd7

commit b9a3a6e9fc748ced98a6479cbbeffffe1e5edbd7
Author: Gyuyoung Kim <gyuyoung@igalia.com>
Date: Tue Jan 22 08:14:17 2019

s13n: Replace some uses of AccountTrackerService in arc_auth_service_browsertest.cc

As a step to remove all uses of ATS, this CL replaces FindAccountInfoByEmail with
FindAccountInfoForAccountWithRefreshTokenByEmailAddress of IdentityManager.
However, RemoveAccount of ATS will be replaced by a follow CL.

Bug: 922747
Change-Id: Ie31ea00fc47eee84bab9fa5c85c3d320920e0497
Reviewed-on: https://chromium-review.googlesource.com/c/1424106
Commit-Queue: Gyuyoung Kim <gyuyoung@igalia.com>
Reviewed-by: Yury Khmel <khmel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#624743}
[modify] https://crrev.com/b9a3a6e9fc748ced98a6479cbbeffffe1e5edbd7/chrome/browser/chromeos/arc/auth/arc_auth_service_browsertest.cc