[iOS] Showing loading content till the plus address is fetched

Bug: 343153116
Change-Id: I1b5c58c0c539b84d54d8cf3cb7fb2a8c217df6a8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5605733


Commit-Queue: Vidhan Jain <vidhanj@google.com>
Reviewed-by: Jan Keitel <jkeitel@google.com>
Cr-Commit-Position: refs/heads/main@{#1312684}