We can put this API in IdentityTestEnvironment::ForceRefreshTokensToUnloadedState() or something similar -- we can bikeshed on the exact name on the CL.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/745381ba737bfdc1a6f678fbbdb066a1f8045693

commit 745381ba737bfdc1a6f678fbbdb066a1f8045693
Author: Antonio Gomes <tonikitoo@igalia.com>
Date: Thu Dec 13 13:45:48 2018

[s13n] Provide replacement API for PO2TS::set_all_credentials_loaded_for_testing

CL is another step forward eliminating all direct calls to PO2TS
APIs from AccountReconcilor unittests. Particularly, it adds a new
API to our testing infrastructure, IdentityTestEnvironment.

BUG= 911641 ,910581

Change-Id: I1ff3a8f287fff0f5b4bfbffe2e2d6943ba36ec52
Reviewed-on: https://chromium-review.googlesource.com/c/1372426
Reviewed-by: David Roger <droger@chromium.org>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Commit-Queue: Antonio Gomes <tonikitoo@igalia.com>
Cr-Commit-Position: refs/heads/master@{#616298}
[modify] https://crrev.com/745381ba737bfdc1a6f678fbbdb066a1f8045693/components/signin/core/browser/account_reconcilor_unittest.cc
[modify] https://crrev.com/745381ba737bfdc1a6f678fbbdb066a1f8045693/services/identity/public/cpp/identity_test_environment.cc
[modify] https://crrev.com/745381ba737bfdc1a6f678fbbdb066a1f8045693/services/identity/public/cpp/identity_test_environment.h