Avoid initial NetworkChangeNotifier OnDNSChanged() signal on Android

net/dns/host_resolver_impl.h

 // Copyright (c) 2012 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_DNS_HOST_RESOLVER_IMPL_H_
 #define NET_DNS_HOST_RESOLVER_IMPL_H_
 
 #include <map>
 
 #include "base/basictypes.h"
@@ skipping 210 matching lines @@
 
   // Attempts to serve each Job in |jobs_| from the HOSTS file if we have
   // a DnsClient with a valid DnsConfig.
   void TryServingAllJobsFromHosts();
 
   // NetworkChangeNotifier::IPAddressObserver:
   void OnIPAddressChanged() override;
 
   // NetworkChangeNotifier::DNSObserver:
   void OnDNSChanged() override;
+  void OnInitialDNSConfigRead() override;
+
+  void UpdateDNSConfig(bool config_changed);
 
   // True if have a DnsClient with a valid DnsConfig.
   bool HaveDnsConfig() const;
 
   // Called when a host name is successfully resolved and DnsTask was run on it
   // and resulted in |net_error|.
   void OnDnsTaskResolve(int net_error);
 
   // Allows the tests to catch slots leaking out of the dispatcher.  One
   // HostResolverImpl::Job could occupy multiple PrioritizedDispatcher job
@@ skipping 53 matching lines @@
   base::WeakPtrFactory<HostResolverImpl> weak_ptr_factory_;
 
   base::WeakPtrFactory<HostResolverImpl> probe_weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(HostResolverImpl);
 };
 
 }  // namespace net
 
 #endif  // NET_DNS_HOST_RESOLVER_IMPL_H_