I'm taking this then

This is being tackled as part of  crbug.com/890824 , so I'm re-assigning it to me (after talking to @svillar, of course)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/522657c3e8b52d65420d23bb993508eee22b43e5

commit 522657c3e8b52d65420d23bb993508eee22b43e5
Author: Mario Sanchez Prada <mario@igalia.com>
Date: Tue Nov 06 18:43:22 2018

[ios] Migrate BookmarkPromoController to the IdentityManager

Rely on the IdentityManager's API instead of SigninManager's one,
and implement identity::IdentityManager::Observer to monitor for
signed-in and signed-out events.

Bug:  890824 ,  887463 
Change-Id: Ic8a7d46ba91c0824d8949475c04fa75131c5cf70
Reviewed-on: https://chromium-review.googlesource.com/c/1315213
Commit-Queue: Mario Sanchez Prada <mario@igalia.com>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605756}
[modify] https://crrev.com/522657c3e8b52d65420d23bb993508eee22b43e5/ios/chrome/browser/ui/bookmarks/bookmark_promo_controller.mm