GitLab

Adds support for provider selection for signed out
users by storing their selection in a pref.

Change-Id: I8f2016556542007e634ef450f1a9fb1f766af33d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2523560Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Tommy Steimel <steimel@chromium.org>
Commit-Queue: Becca Hughes <beccahughes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826018}