I need this one before I can provide a CL for 890796, assigning.

There still a few things that need to be in place before this can be fixed, but I put a WIP CL in https://chromium-review.googlesource.com/c/chromium/src/+/1261637 in the meantime.

> I need this one before I can provide a CL for 890796, assigning.

Actually, it's the other way around I just noticed: once 889863 and 890794 are fixed, this can be ported with the exception of the call to GetStatusLabels(), that will need to receive a SigninManager until 890796 gets fixed.

Updating WIP CL and deps...

I've split the bits unrelated to IdentityManager::Observer to  crbug.com/898810 , so this is no longer blocked on issues  890794  and  890796 .

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/35af51e397a46b2adb8a27a305e58b97559208a2

commit 35af51e397a46b2adb8a27a305e58b97559208a2
Author: Mario Sanchez Prada <mario@igalia.com>
Date: Fri Oct 26 09:51:38 2018

Convert PeopleHandler to IdentityManager::Observer

Reimplement callbacks GoogleSigninSucceeded and GoogleSignedOut as
OnPrimaryAccountSet and OnPrimaryAccountCleared, from IdentityManager.

Bug:  887461 
Change-Id: I6a0f5758b8c07f21a8b06b4993a9f58528ee7c7e
Reviewed-on: https://chromium-review.googlesource.com/c/1261637
Commit-Queue: Mario Sanchez Prada <mario@igalia.com>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603044}
[modify] https://crrev.com/35af51e397a46b2adb8a27a305e58b97559208a2/chrome/browser/ui/webui/settings/people_handler.cc
[modify] https://crrev.com/35af51e397a46b2adb8a27a305e58b97559208a2/chrome/browser/ui/webui/settings/people_handler.h