[ios] add manual fallback address mediator

Bug: 845472
Change-Id: I6ba687245c8493d21bc305c1f530146ef97e59aa
Reviewed-on: https://chromium-review.googlesource.com/c/1318972
Commit-Queue: David Jean <djean@chromium.org>
Reviewed-by: Moe Ahmadi <mahmadi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606533}
4 files changed