I'm taking this

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9d3e7edfbf68c9f69f720c49a40a6b51c2656383

commit 9d3e7edfbf68c9f69f720c49a40a6b51c2656383
Author: Sergio Villar Senin <svillar@igalia.com>
Date: Tue Jan 15 11:06:16 2019

Convert FamilyInfoFetcher to use IdentityManager

It was using ProfileOAuth2TokenService to request and track refresh
tokens for family accounts. That could be done with the
IdentityManager API.

A new API was added to IdentityTestEnvironment to reload the
credentials from persistent storage. That was needed by one of the
unit tests.

Bug:  912145 
Change-Id: I0502840c4f14e108da720be6a1bce93a20f34278
Reviewed-on: https://chromium-review.googlesource.com/c/1394523
Reviewed-by: Colin Blundell <blundell@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Sergio Villar <svillar@igalia.com>
Cr-Commit-Position: refs/heads/master@{#622810}
[modify] https://crrev.com/9d3e7edfbf68c9f69f720c49a40a6b51c2656383/chrome/browser/supervised_user/child_accounts/child_account_service.cc
[modify] https://crrev.com/9d3e7edfbf68c9f69f720c49a40a6b51c2656383/chrome/browser/supervised_user/child_accounts/family_info_fetcher.cc
[modify] https://crrev.com/9d3e7edfbf68c9f69f720c49a40a6b51c2656383/chrome/browser/supervised_user/child_accounts/family_info_fetcher.h
[modify] https://crrev.com/9d3e7edfbf68c9f69f720c49a40a6b51c2656383/chrome/browser/supervised_user/child_accounts/family_info_fetcher_unittest.cc
[modify] https://crrev.com/9d3e7edfbf68c9f69f720c49a40a6b51c2656383/services/identity/public/cpp/identity_test_environment.cc
[modify] https://crrev.com/9d3e7edfbf68c9f69f720c49a40a6b51c2656383/services/identity/public/cpp/identity_test_environment.h