The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9ef7e0e855bb5f39a3c32daf3b988d731d4a47b4

commit 9ef7e0e855bb5f39a3c32daf3b988d731d4a47b4
Author: Florian Uunk <feuunk@chromium.org>
Date: Thu Aug 30 12:54:32 2018

Switch PersonalDataManager storage based on sync

PersonalDataManager now checks the sync feature state in its
OnStateChanged method, and if the sync the feature is not on, it will
use the ephemeral account storage, instead of the persistent store.

Note that we previously wanted to use the USS bridge as a source of this
information, instead of observing the sync service directly. However,
using that approach means that all updates need to switch from the db
thread to the main thread. That could mean that while an account switch
update is underway from the bridge to PDM, the PDM is still committing
changes to the database for the previous account.

A cleaner fix may be to do the entire switch on the database thread, at
which point PDM only needs to be notified that the storage changed.

Bug:  878858 
Change-Id: I6581eb45f7e3510142142e25ede5e8b296fcaf9d
Reviewed-on: https://chromium-review.googlesource.com/1194126
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#587536}
[modify] https://crrev.com/9ef7e0e855bb5f39a3c32daf3b988d731d4a47b4/chrome/browser/autofill/personal_data_manager_factory.cc
[modify] https://crrev.com/9ef7e0e855bb5f39a3c32daf3b988d731d4a47b4/components/autofill/core/browser/personal_data_manager.cc
[modify] https://crrev.com/9ef7e0e855bb5f39a3c32daf3b988d731d4a47b4/components/autofill/core/browser/personal_data_manager.h
[modify] https://crrev.com/9ef7e0e855bb5f39a3c32daf3b988d731d4a47b4/components/autofill/core/browser/personal_data_manager_unittest.cc
[modify] https://crrev.com/9ef7e0e855bb5f39a3c32daf3b988d731d4a47b4/components/autofill/core/browser/test_sync_service.cc
[modify] https://crrev.com/9ef7e0e855bb5f39a3c32daf3b988d731d4a47b4/components/autofill/core/browser/test_sync_service.h
[modify] https://crrev.com/9ef7e0e855bb5f39a3c32daf3b988d731d4a47b4/components/browser_sync/profile_sync_service_autofill_unittest.cc