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

net/dns/dns_session.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 "net/dns/dns_session.h"
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/lazy_instance.h"
 #include "base/metrics/histogram.h"
@@ skipping 211 matching lines @@
   return std::min(timeout * (1 << num_backoffs),
                   base::TimeDelta::FromMilliseconds(kMaxTimeoutMs));
 }
 
 // Allocate a socket, already connected to the server address.
 scoped_ptr<DnsSession::SocketLease> DnsSession::AllocateSocket(
     unsigned server_index, const NetLog::Source& source) {
   scoped_ptr<DatagramClientSocket> socket;
 
   socket = socket_pool_->AllocateSocket(server_index);
-  if (!socket.get()) return scoped_ptr<SocketLease>(NULL);
+  if (!socket.get())
+    return scoped_ptr<SocketLease>();
 
   socket->NetLog().BeginEvent(NetLog::TYPE_SOCKET_IN_USE,
                               source.ToEventParametersCallback());
 
   SocketLease* lease = new SocketLease(this, server_index, socket.Pass());
   return scoped_ptr<SocketLease>(lease);
 }
 
 scoped_ptr<StreamSocket> DnsSession::CreateTCPSocket(
     unsigned server_index, const NetLog::Source& source) {
@@ skipping 51 matching lines @@
   timeout = std::max(timeout, base::TimeDelta::FromMilliseconds(kMinTimeoutMs));
 
   // The timeout still doubles every full round.
   unsigned num_backoffs = attempt / config_.nameservers.size();
 
   return std::min(timeout * (1 << num_backoffs),
                   base::TimeDelta::FromMilliseconds(kMaxTimeoutMs));
 }
 
 }  // namespace net