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

chrome/browser/net/dns_probe_service_unittest.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/bind.h"
 #include "base/compiler_specific.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop.h"
@@ skipping 70 matching lines @@
 
   bool system_job_created_;
   bool public_job_created_;
 
  private:
   // Override methods in DnsProbeService to return mock jobs:
 
   virtual scoped_ptr<DnsProbeJob> CreateSystemProbeJob(
       const DnsProbeJob::CallbackType& job_callback) OVERRIDE {
     if (mock_system_fail_)
-      return scoped_ptr<DnsProbeJob>(NULL);
+      return scoped_ptr<DnsProbeJob>();
 
     system_job_created_ = true;
     return scoped_ptr<DnsProbeJob>(
         new MockDnsProbeJob(job_callback,
                             mock_system_result_));
   }
 
   virtual scoped_ptr<DnsProbeJob> CreatePublicProbeJob(
       const DnsProbeJob::CallbackType& job_callback) OVERRIDE {
     public_job_created_ = true;
@@ skipping 109 matching lines @@
 
   Reset();
 
   RunUntilIdle();
   EXPECT_FALSE(callback_called_);
 }
 
 }  // namespace
 
 }  // namespace chrome_browser_net