GitLab

It was using SigninManagerBase API to get the primary (authenticated)
account id. It's now using the IdentityManager API.

Bug: 890792
Change-Id: Ia8cdd8e491f29256af2c015a9127b0766e81b99e
Reviewed-on: https://chromium-review.googlesource.com/c/1276965
Commit-Queue: Sergio Villar <svillar@igalia.com>
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599173}