CL https://chromium-review.googlesource.com/c/chromium/src/+/1340890.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d22ab991da0abcd793f0cbbeb79ae29d9cbcb831

commit d22ab991da0abcd793f0cbbeb79ae29d9cbcb831
Author: Antonio Gomes <tonikitoo@igalia.com>
Date: Wed Nov 21 13:35:07 2018

[s13n] Port identity_api.cc away from observing ProfileOAuth2TokenService

... to observing IdentityManager

CL also gets rid of the AccountTrackerService usage, driven-by.

BUG= 906579 

Change-Id: I1ec47f5817a665995a5c1e4c2a6ed21a49756f3e
Reviewed-on: https://chromium-review.googlesource.com/c/1340890
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Commit-Queue: Antonio Gomes <tonikitoo@igalia.com>
Cr-Commit-Position: refs/heads/master@{#610032}
[modify] https://crrev.com/d22ab991da0abcd793f0cbbeb79ae29d9cbcb831/chrome/browser/extensions/api/identity/identity_api.cc
[modify] https://crrev.com/d22ab991da0abcd793f0cbbeb79ae29d9cbcb831/chrome/browser/extensions/api/identity/identity_api.h