Reland: Lazily initialize MessageLoop for faster thread startup

net/android/network_change_notifier_android.cc

 // 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.
 
 ////////////////////////////////////////////////////////////////////////////////
 // Threading considerations:
 //
 // This class is designed to meet various threading guarantees starting from the
 // ones imposed by NetworkChangeNotifier:
 // - The notifier can be constructed on any thread.
@@ skipping 155 matching lines @@
 NetworkChangeNotifierAndroid::NetworkChangeNotifierAndroid(
     NetworkChangeNotifierDelegateAndroid* delegate,
     const DnsConfig* dns_config_for_testing)
     : NetworkChangeNotifier(NetworkChangeCalculatorParamsAndroid()),
       delegate_(delegate),
       dns_config_service_thread_(
           new DnsConfigServiceThread(dns_config_for_testing)) {
   delegate_->AddObserver(this);
   dns_config_service_thread_->StartWithOptions(
       base::Thread::Options(base::MessageLoop::TYPE_IO, 0));
+  // Wait until Init is called on the DNS config thread before
+  // calling InitAfterStart.
+  dns_config_service_thread_->WaitUntilThreadStarted();
   dns_config_service_thread_->InitAfterStart();
 }
 
 // static
 NetworkChangeNotifier::NetworkChangeCalculatorParams
 NetworkChangeNotifierAndroid::NetworkChangeCalculatorParamsAndroid() {
   NetworkChangeCalculatorParams params;
   // IPAddressChanged is produced immediately prior to ConnectionTypeChanged
   // so delay IPAddressChanged so they get merged with the following
   // ConnectionTypeChanged signal.
   params.ip_address_offline_delay_ = base::TimeDelta::FromSeconds(1);
   params.ip_address_online_delay_ = base::TimeDelta::FromSeconds(1);
   params.connection_type_offline_delay_ = base::TimeDelta::FromSeconds(0);
   params.connection_type_online_delay_ = base::TimeDelta::FromSeconds(0);
   return params;
 }
 
 }  // namespace net