GitLab

Use URLLoaderInterceptor instead to provide content for other tests.
Disabled a few tests that were testing implementation of
GenericURLRequestJob & co, as the net/-specific code in headless is
going away.

Change-Id: I538528292f009d1b1a1148f8ded2c9a284a320e9
Reviewed-on: https://chromium-review.googlesource.com/1128509
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573566}