Rewrite HttpIceConfigRequestTest not to mock results

This CL is a follow up of [1], where remoting::ChromiumUrlRequest
migrated away from URLFetcher to SimpleURLLoader.

During the migration, it was observed the ChromiumUrlRequest actual
fetch/load machinery was not exercised at all by tests.
This CL is a first step to fill this gap: rather than fully
mock remoting::UrlRequest results, it now makes use of
TestURLLoaderFactory and ChromiumUrlRequest.

BUG=773295

Change-Id: Ie93fca014d4ae7186cfae9582568657476e5fd88
Reviewed-on: https://chromium-review.googlesource.com/1194622
Commit-Queue: Antonio Gomes <tonikitoo@igalia.com>
Reviewed-by: Joe Downing <joedow@chromium.org>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586878}
2 files changed