commit de0c56658db11e0597f58a14ee65ed75d6e02abd
author Eric Orth <ericorth@chromium.org> Tue Jun 25 15:36:02 2019
committer Commit Bot <commit-bot@chromium.org> Tue Jun 25 15:36:02 2019
tree 389fa6f2c958ba1e55543dc66a84c69f8a0f0636
parent ba345fef12ea7eab8b5637d17390e7749ec31ac6

Create a notifier class for system DNS config changes

Essentially a thread-safe notifier wrapping around DnsConfigService,
intended (but not yet used) for NetworkChangeNotifier and
HostResolverManager(s) to listen to a shared object for system DNS
config changes. In subsequent CLs, this will allow us to divorce
HostResolverManager from listening to NetworkChangeNotifier and be able
to apply Chrome-internal config changes on top of the system-only
changes currently triggerring change notifications.

In non-test, will generally be expected to be broadly shared and leaked
on shutdown.  Sequence-safe destruction is still implemented (using an
internal Core class with an OnTaskRunnerDeleter) for any special cases
and for tests.

Note that some of the internal workings of the new class work similarly
to base::ObserverListThreadSafe, but it was too difficult to make that
work with the requirement that we always be able to get an initial
config once ready, whether read before or after adding observers.

Bug: 971411
Change-Id: Iac79dba9f74018ae6b9559c27df60174bf4edc93
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1654881
Reviewed-by: Matt Menke <mmenke@chromium.org>
Commit-Queue: Eric Orth <ericorth@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672087}