[ios] Final part of removing UrlLoader from ios

Bug: 907527
Change-Id: I582915db895abfb922c221bd2197f0ea1dff6368
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1547514
Commit-Queue: David Jean <djean@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#650726}
12 files changed