I can do this one.

Where should it go?

I'm not sure. It's related to this though: https://codesearch.chromium.org/chromium/src/net/url_request/url_request_http_job.cc?rcl=efddbe79f23b2ecbaf250302bd70c4fd82c002dd&l=81

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/dbf45973be46d9dd01f8d7d3dadddef0eeeaff06

commit dbf45973be46d9dd01f8d7d3dadddef0eeeaff06
Author: tfarina <tfarina@chromium.org>
Date: Tue May 09 04:36:09 2017

net: add IsMethodSafe() method to HttpUtil

This consolidates the three copies of it in a single and accessible place.

BUG= 675760 
TEST=net_unittests
R=mmenke@chromium.org

Review-Url: https://codereview.chromium.org/2860323002
Cr-Commit-Position: refs/heads/master@{#470211}

[modify] https://crrev.com/dbf45973be46d9dd01f8d7d3dadddef0eeeaff06/headless/lib/headless_browser_browsertest.cc
[modify] https://crrev.com/dbf45973be46d9dd01f8d7d3dadddef0eeeaff06/headless/public/util/generic_url_request_job.cc
[modify] https://crrev.com/dbf45973be46d9dd01f8d7d3dadddef0eeeaff06/net/http/http_util.cc
[modify] https://crrev.com/dbf45973be46d9dd01f8d7d3dadddef0eeeaff06/net/http/http_util.h
[modify] https://crrev.com/dbf45973be46d9dd01f8d7d3dadddef0eeeaff06/net/url_request/url_request_http_job.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4f4a5a7103aa313f038ce2990cbdad50ae2ef9c1

commit 4f4a5a7103aa313f038ce2990cbdad50ae2ef9c1
Author: tfarina <tfarina@chromium.org>
Date: Wed May 10 13:03:03 2017

net: add IsMethodIdempotent() to HttpUtil

It goes hand to hand with IsMethodSafe() and is not something
that is specific to the data reduction proxy. So it is better
to keep it in HttpUtil.

BUG= 675760 
TEST=net_unittests
R=mmenke@chromium.org,bengr@chromium.org

Review-Url: https://codereview.chromium.org/2871913004
Cr-Commit-Position: refs/heads/master@{#470546}

[modify] https://crrev.com/4f4a5a7103aa313f038ce2990cbdad50ae2ef9c1/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol.cc
[modify] https://crrev.com/4f4a5a7103aa313f038ce2990cbdad50ae2ef9c1/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol_unittest.cc
[modify] https://crrev.com/4f4a5a7103aa313f038ce2990cbdad50ae2ef9c1/components/data_reduction_proxy/core/common/data_reduction_proxy_util.cc
[modify] https://crrev.com/4f4a5a7103aa313f038ce2990cbdad50ae2ef9c1/components/data_reduction_proxy/core/common/data_reduction_proxy_util.h
[modify] https://crrev.com/4f4a5a7103aa313f038ce2990cbdad50ae2ef9c1/net/http/http_util.cc
[modify] https://crrev.com/4f4a5a7103aa313f038ce2990cbdad50ae2ef9c1/net/http/http_util.h