Ryan: Given that none of our bots run with this configuration, I'm curious how you propose to prevent this routinely bitrotting?

Many of our tests now rely on the hermeticism from the swarming framework. Multiple efforts to ensure intra-test hermeticism were abandoned upon the completion of swarming - recognizing that it is perhaps not achievable with the constraints and infrastructure we have.

What motivates this change? Is there another way we can accomplish that?

3 days ago  crbug.com/728808  was filed about a particular test which caused other tests to fail on iOS. So I believe that at least iOS is still running with this configuration.  In addition when running tests locally, --single-process-tests is used under the hood to group tests together. If there are conflicting tests in a particular group then that introduces spurious failures which need to be retried, leading to increased runtime. From my testing over the weekend, I believe there are only two net_unittests which are currently problematic in this respect. I have a CL out the fix the first, and hopefully fixing the second won't be terribly problematic.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ce64e673564b8a2b0912c07567e96c97aa4dca06

commit ce64e673564b8a2b0912c07567e96c97aa4dca06
Author: rch <rch@chromium.org>
Date: Mon Jun 05 17:41:57 2017

Change HostResolverImplDnsTest.NoIPv6OnWifi to no longer leak
deleted resolvers into the network change notifier.

BUG= 729320 , 728808 

Review-Url: https://codereview.chromium.org/2916903006
Cr-Commit-Position: refs/heads/master@{#477013}

[modify] https://crrev.com/ce64e673564b8a2b0912c07567e96c97aa4dca06/net/dns/host_resolver_impl_unittest.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ce64e673564b8a2b0912c07567e96c97aa4dca06

commit ce64e673564b8a2b0912c07567e96c97aa4dca06
Author: rch <rch@chromium.org>
Date: Mon Jun 05 17:41:57 2017

Change HostResolverImplDnsTest.NoIPv6OnWifi to no longer leak
deleted resolvers into the network change notifier.

BUG= 729320 , 728808 

Review-Url: https://codereview.chromium.org/2916903006
Cr-Commit-Position: refs/heads/master@{#477013}

[modify] https://crrev.com/ce64e673564b8a2b0912c07567e96c97aa4dca06/net/dns/host_resolver_impl_unittest.cc