Updating the bug to reflect the current state of the world and be scoped to PO2TS; ProfileChooserView already no longer uses SigninManager and there's just a stale include there that should be removed.

ProfileChooserView observes PO2TS and revokes refresh tokens. For the former, it will observe IdentityManager; for the latter, it should use AccountsMutator. We need to bring up the APIs for revoking fresh tokens in the latter (see blocking bug).

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/93cae7faa893a055c6a832396666f58815e1256a

commit 93cae7faa893a055c6a832396666f58815e1256a
Author: Mario Sanchez Prada <mario@igalia.com>
Date: Thu Jan 10 16:28:25 2019

Port ProfileChooserView away from using ProfileOAuth2TokenService

Move to implementing identity::IdentityManager::Observer now and to
using the AccountsMutator's API to remove accounts, instead of relying
on the APIs from ProfileOAuth2TokenService.

Bug:  808989 
Change-Id: I649f1927eee670744c26255351d77cdbc0fd0a2d
Reviewed-on: https://chromium-review.googlesource.com/c/1377854
Commit-Queue: Mario Sanchez Prada <mario@igalia.com>
Reviewed-by: Thomas Tangl <tangltom@chromium.org>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#621595}
[modify] https://crrev.com/93cae7faa893a055c6a832396666f58815e1256a/chrome/browser/ui/views/profiles/profile_chooser_view.cc
[modify] https://crrev.com/93cae7faa893a055c6a832396666f58815e1256a/chrome/browser/ui/views/profiles/profile_chooser_view.h