GitLab

Removes most usage of scoped_nsobject in ios/, except

- ios/web/net/request_tracker_impl.{h|mm}
- ios/web/public

Bug: 717540
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I02cff4e1786f7405d055faf1ca7f8b1cc40ac417
Reviewed-on: https://chromium-review.googlesource.com/846803
Commit-Queue: Stepan Khapugin <stkhapugin@chromium.org>
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#526673}