[iOS][Unity] Fixing issue to open automatically the identity chooser dialog

Adding -UnifiedConsentCoordinator.identitySelectedByUser to track when
the user selects an identity. This is to make sure the identity chooser
dialog is opened automatically only when the user didn't select an
identity yet.

Bug: 896709
Cq-Include-Trybots: luci.chromium.try:ios-simulator-cronet;luci.chromium.try:ios-simulator-full-configs
Change-Id: Ib849ac7d385910398f62bf7e7e933f79983e3691
Reviewed-on: https://chromium-review.googlesource.com/c/1288790
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Jérôme Lebel <jlebel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601097}
2 files changed