GitLab

This CL migrates ProfileSyncService to IdentityManager for getting
info on the primary account. This includes switching from
SigninManagerBase::Observer to IdentityManager::Observer.
The only remaining use of SigninManager within PSS it to call
SignOut() which isn't exposed by IdentityManager yet.

Bug: 825190
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: Icf9398d63794cab03cb559adba5c767e18c31c0a
Reviewed-on: https://chromium-review.googlesource.com/983914
Commit-Queue: Marc Treib <treib@chromium.org>
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553973}