Add Data Saver ChromeDriver test for MissingViaHeader4xx bypass behavior

Add Data Saver ChromeDriver test for MissingViaHeader4xx bypass behavior

This test attempts to load a page through a test proxy that doesn't set
the via header properly on a 4xx-error response, and verifies that
Chrome bypasses all proxies and retries the request over direct.

BUG=700612
Review-Url: https://codereview.chromium.org/2742693006
Cr-Commit-Position: refs/heads/master@{#456809}
Committed: https://chromium.googlesource.com/chromium/src/+/ee873e760f26ecebde137f160a2673ae83359bd3

[sclittle, 2017-03-11 02:32:27]

sclittle@chromium.org changed reviewers:
+ megjablon@chromium.org, robertogden@chromium.org

[megjablon, 2017-03-14 17:39:26]

lgtm

[Robert Ogden, 2017-03-14 18:18:07]

lgtm

[sclittle, 2017-03-14 19:28:40]

The CQ bit was checked by sclittle@chromium.org

[sclittle, 2017-03-14 19:28:40]

The patchset sent to the CQ was uploaded after l-g-t-m from
robertogden@chromium.org, megjablon@chromium.org
Link to the patchset: https://codereview.chromium.org/2742693006/#ps20001
(title: "Rebased on master")

[commit-bot: I haz the power, 2017-03-14 19:29:49]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-14 20:17:02]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1489519720253320,
"parent_rev": "44f45ea28f832edfdd3d8ddad75b7a93101711d9", "commit_rev":
"ee873e760f26ecebde137f160a2673ae83359bd3"}

[commit-bot: I haz the power, 2017-03-14 20:17:44]

Description was changed from

==========
Add Data Saver ChromeDriver test for MissingViaHeader4xx bypass behavior

This test attempts to load a page through a test proxy that doesn't set
the via header properly on a 4xx-error response, and verifies that
Chrome bypasses all proxies and retries the request over direct.

BUG=700612
==========

to

==========
Add Data Saver ChromeDriver test for MissingViaHeader4xx bypass behavior

This test attempts to load a page through a test proxy that doesn't set
the via header properly on a 4xx-error response, and verifies that
Chrome bypasses all proxies and retries the request over direct.

BUG=700612

Review-Url: https://codereview.chromium.org/2742693006
Cr-Commit-Position: refs/heads/master@{#456809}
Committed:
https://chromium.googlesource.com/chromium/src/+/ee873e760f26ecebde137f160a26...
==========

[commit-bot: I haz the power, 2017-03-14 20:17:45]

Committed patchset #2 (id:20001) as
https://chromium.googlesource.com/chromium/src/+/ee873e760f26ecebde137f160a26...