The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/16b57289a75cdf261f5aaea4bd5b3dacc4bbab96

commit 16b57289a75cdf261f5aaea4bd5b3dacc4bbab96
Author: Mario Sanchez Prada <mario@igalia.com>
Date: Tue Oct 23 17:45:56 2018

Convert UserPolicySigninService[Base] to IdentityManager::Observer

This patch converts both classes at the same time due to the
interdependencies (e.g. signin_manager() helper) that would make
it harder to do it separately.

TBR=msarda@chromium.org

Bug:  887449 ,  887450 ,  890783 ,  890782 ,  890782 
Change-Id: Ia5d2834e449c7da635445e0baea2910b23903596
Reviewed-on: https://chromium-review.googlesource.com/c/1290931
Commit-Queue: Mario Sanchez Prada <mario@igalia.com>
Reviewed-by: Sergey Poromov <poromov@chromium.org>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602005}
[modify] https://crrev.com/16b57289a75cdf261f5aaea4bd5b3dacc4bbab96/chrome/browser/policy/cloud/user_policy_signin_service.cc
[modify] https://crrev.com/16b57289a75cdf261f5aaea4bd5b3dacc4bbab96/chrome/browser/policy/cloud/user_policy_signin_service.h
[modify] https://crrev.com/16b57289a75cdf261f5aaea4bd5b3dacc4bbab96/chrome/browser/policy/cloud/user_policy_signin_service_base.cc
[modify] https://crrev.com/16b57289a75cdf261f5aaea4bd5b3dacc4bbab96/chrome/browser/policy/cloud/user_policy_signin_service_base.h
[modify] https://crrev.com/16b57289a75cdf261f5aaea4bd5b3dacc4bbab96/chrome/browser/policy/cloud/user_policy_signin_service_factory.cc
[modify] https://crrev.com/16b57289a75cdf261f5aaea4bd5b3dacc4bbab96/chrome/browser/policy/cloud/user_policy_signin_service_mobile.cc
[modify] https://crrev.com/16b57289a75cdf261f5aaea4bd5b3dacc4bbab96/chrome/browser/policy/cloud/user_policy_signin_service_mobile.h
[modify] https://crrev.com/16b57289a75cdf261f5aaea4bd5b3dacc4bbab96/chrome/browser/policy/cloud/user_policy_signin_service_unittest.cc
[modify] https://crrev.com/16b57289a75cdf261f5aaea4bd5b3dacc4bbab96/chrome/browser/ui/webui/signin/dice_turn_sync_on_helper_unittest.cc