The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/98eb1559c03380abcea7df745a0d5ff9eb63c440

commit 98eb1559c03380abcea7df745a0d5ff9eb63c440
Author: Robert Ogden <robertogden@chromium.org>
Date: Wed Jan 24 17:37:51 2018

Add proxy blackhole test

Checks that the DRP proxy is not used and the page is loaded directly
when the proxy is a TCP blackhole

Bug:  805072 
Change-Id: I14c8e61c8a8d412360e167a5c2fc13863e9e185c
Reviewed-on: https://chromium-review.googlesource.com/881869
Commit-Queue: Robert Ogden <robertogden@google.com>
Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531587}
[modify] https://crrev.com/98eb1559c03380abcea7df745a0d5ff9eb63c440/tools/chrome_proxy/webdriver/emulation_server.py
[modify] https://crrev.com/98eb1559c03380abcea7df745a0d5ff9eb63c440/tools/chrome_proxy/webdriver/proxy_connection.py