Linux: Monitor resolv.conf for changes and use that to reload resolver.

net/base/dns_reloader.h

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef NET_BASE_DNS_RELOADER_H_
+#define NET_BASE_DNS_RELOADER_H_
+#pragma once
+
+#include "build/build_config.h"
+
+#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD)
+namespace net {
+
+// Call on the network thread before calling DnsReloaderMaybeReload() anywhere.
+void EnsureDnsReloaderInit();
+
+// Call on the worker thread before doing a DNS lookup to reload the
+// resolver for that thread by doing res_ninit() if required.
+void DnsReloaderMaybeReload();
+
+}  // namespace net
+#endif  // defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD)
+
+#endif  // NET_BASE_DNS_RELOADER_H_