The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0d37fb92c058ad2c170e07812b3b2cc0154c4342

commit 0d37fb92c058ad2c170e07812b3b2cc0154c4342
Author: Sylvain Defresne <sdefresne@chromium.org>
Date: Tue Dec 11 12:46:42 2018

Add API to convert AccountTrackerService::FindAccountInfoByXXX

Add methods to find AccountInfo using either account id, email
address or gaia id to IdentityManager. They are wrapper around
the corresponding method of AccountTrackerService (with a call
to GetAccountInfoForAccountWithValidRefreshToken to get the
logic to deal with kSupervisedUserPseudoEmail).

Add unit tests for the new methods.

Bug: 912170
Change-Id: Ic7da17b0f22c85349b89cb44d272a3a6b4f6d573
Reviewed-on: https://chromium-review.googlesource.com/c/1365245
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615502}
[modify] https://crrev.com/0d37fb92c058ad2c170e07812b3b2cc0154c4342/services/identity/public/cpp/identity_manager.cc
[modify] https://crrev.com/0d37fb92c058ad2c170e07812b3b2cc0154c4342/services/identity/public/cpp/identity_manager.h
[modify] https://crrev.com/0d37fb92c058ad2c170e07812b3b2cc0154c4342/services/identity/public/cpp/identity_manager_unittest.cc

Moving to P2 to reflect that current milestone is for completing conversion of PO2TS/SigninManager.