Rewrite scoped_ptr<T>(NULL) to use the default ctor in chrome/.

chrome/browser/net/dns_probe_service.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.
 
 #include "chrome/browser/net/dns_probe_service.h"
 
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string_number_conversions.h"
 #include "chrome/browser/net/dns_probe_job.h"
@@ skipping 257 matching lines @@
   for (std::vector<CallbackType>::const_iterator i = callbacks.begin();
        i != callbacks.end(); ++i) {
     i->Run(result_);
   }
 }
 
 scoped_ptr<DnsProbeJob> DnsProbeService::CreateProbeJob(
     const DnsConfig& dns_config,
     const DnsProbeJob::CallbackType& job_callback) {
   if (!dns_config.IsValid())
-    return scoped_ptr<DnsProbeJob>(NULL);
+    return scoped_ptr<DnsProbeJob>();
 
   scoped_ptr<DnsClient> dns_client(DnsClient::CreateClient(NULL));
   dns_client->SetConfig(dns_config);
   return DnsProbeJob::CreateJob(dns_client.Pass(), job_callback, NULL);
 }
 
 void DnsProbeService::OnProbeJobComplete(DnsProbeJob* job,
                                          DnsProbeJob::Result result) {
   DCHECK_EQ(STATE_PROBE_RUNNING, state_);
 
@@ skipping 46 matching lines @@
   config->randomize_ports = false;
 }
 
 bool DnsProbeService::ResultsExpired() {
   const base::TimeDelta kMaxResultAge =
       base::TimeDelta::FromMilliseconds(kMaxResultAgeMs);
   return base::Time::Now() - probe_start_time_ > kMaxResultAge;
 }
 
 } // namespace chrome_browser_net