GitLab

1) Use url_loader instead of URLRequest.
2) Use network_connection_tracker instead of
   network change notifier.

Bug: internal b/139539332
Change-Id: Ia84e3d62d22fd97d440ecf7e148ce8e663a9568d
Merge-With: eureka-internal/255804
Merge-With: eureka-internal/305059
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1762598
Commit-Queue: Mohit Hotwani <hmohit@chromium.org>
Reviewed-by: Maks Orlovich <morlovich@chromium.org>
Reviewed-by: Junbo Ke <juke@chromium.org>
Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#690453}