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The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1842b8ccebf3d914b7aed7702b50223c072e5fcc

commit 1842b8ccebf3d914b7aed7702b50223c072e5fcc
Author: John Abd-El-Malek <jam@chromium.org>
Date: Wed May 16 14:53:22 2018

Fix content_browsertests flakiness on Win Mojo FYI bot.

The problem, while not specific to these tests, manifested in the download tests sometimes hanging.
The cause was that the initial reading of DNS configuration was cancelling in-progress host
resolver queries. This showed up in these particular tests because they loaded requests immediately
(e.g. without going through the renderer) on startup and were using the (mock) host resolver. Other
tests usually spin up a renderer, which would delay requests through the network and this bug would
be masked.

This was solved previously for Android in  http://crbug.com/470897 . This change fixes it for all
platforms. It also simplifies the previous fix, since later in r391799 the code stopped using time
comparisons and just used a boolean to store whether it was the first dns setting or not.

Bug:  841557 ,  470897 
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_mojo
Change-Id: I3b0a081098a3e3400881c88e64a7f2ce2797f728
Reviewed-on: https://chromium-review.googlesource.com/1055111
Reviewed-by: Paul Jensen <pauljensen@chromium.org>
Commit-Queue: John Abd-El-Malek <jam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559089}
[modify] https://crrev.com/1842b8ccebf3d914b7aed7702b50223c072e5fcc/components/certificate_transparency/mock_log_dns_traffic.cc
[modify] https://crrev.com/1842b8ccebf3d914b7aed7702b50223c072e5fcc/net/android/network_change_notifier_android.cc
[modify] https://crrev.com/1842b8ccebf3d914b7aed7702b50223c072e5fcc/net/android/network_change_notifier_android.h
[modify] https://crrev.com/1842b8ccebf3d914b7aed7702b50223c072e5fcc/net/android/network_change_notifier_android_unittest.cc
[modify] https://crrev.com/1842b8ccebf3d914b7aed7702b50223c072e5fcc/net/android/network_change_notifier_factory_android.cc
[modify] https://crrev.com/1842b8ccebf3d914b7aed7702b50223c072e5fcc/net/base/network_change_notifier.cc
[modify] https://crrev.com/1842b8ccebf3d914b7aed7702b50223c072e5fcc/net/base/network_change_notifier.h
[modify] https://crrev.com/1842b8ccebf3d914b7aed7702b50223c072e5fcc/net/dns/dns_config_service_posix.cc
[modify] https://crrev.com/1842b8ccebf3d914b7aed7702b50223c072e5fcc/net/dns/dns_config_service_posix.h
[modify] https://crrev.com/1842b8ccebf3d914b7aed7702b50223c072e5fcc/net/dns/dns_config_service_posix_unittest.cc
[modify] https://crrev.com/1842b8ccebf3d914b7aed7702b50223c072e5fcc/net/dns/host_resolver_impl_unittest.cc
[modify] https://crrev.com/1842b8ccebf3d914b7aed7702b50223c072e5fcc/services/network/network_context_cert_transparency_unittest.cc