Fixed with https://critique.corp.google.com/#review/216858072 (iOS) and https://critique.corp.google.com/#review/216528889 (Android)

Because of  issue 902584 . We have to reopen this bug.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b7ed9196cf3fde62117161f9c649ae9aad370d1f

commit b7ed9196cf3fde62117161f9c649ae9aad370d1f
Author: Jérôme Lebel <jlebel@chromium.org>
Date: Thu Nov 29 12:09:44 2018

[iOS] kUseMultiloginEndpoint linked to kWKHTTPSystemCookieStore

kUseMultiloginEndpoint can only be enabled if kWKHTTPSystemCookieStore
is enabled. CookieManager::SetCanonicalCookie() fails to store the
cookies.

Bug:  902584 , 892130
Change-Id: If3ba635f031e7de830c87b7a97fd262a9e6e2cee
Reviewed-on: https://chromium-review.googlesource.com/c/1352324
Commit-Queue: Jérôme Lebel <jlebel@chromium.org>
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612157}
[modify] https://crrev.com/b7ed9196cf3fde62117161f9c649ae9aad370d1f/components/signin/core/browser/account_reconcilor.cc
[modify] https://crrev.com/b7ed9196cf3fde62117161f9c649ae9aad370d1f/components/signin/core/browser/account_reconcilor.h
[modify] https://crrev.com/b7ed9196cf3fde62117161f9c649ae9aad370d1f/components/signin/core/browser/account_reconcilor_unittest.cc
[modify] https://crrev.com/b7ed9196cf3fde62117161f9c649ae9aad370d1f/ios/chrome/browser/signin/account_reconcilor_factory.cc