Cleanup usage of scoped_ptr<> in remoting for C++11

remoting/protocol/audio_writer.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 "remoting/protocol/audio_writer.h"
 
 #include "base/bind.h"
 #include "net/socket/stream_socket.h"
 #include "remoting/base/constants.h"
 #include "remoting/proto/audio.pb.h"
@@ skipping 18 matching lines @@
 }
 
 void AudioWriter::ProcessAudioPacket(scoped_ptr<AudioPacket> packet,
                                      const base::Closure& done) {
   buffered_writer_.Write(SerializeAndFrameMessage(*packet), done);
 }
 
 // static
 scoped_ptr<AudioWriter> AudioWriter::Create(const SessionConfig& config) {
   if (!config.is_audio_enabled())
-    return scoped_ptr<AudioWriter>();
+    return nullptr;
   // TODO(kxing): Support different session configurations.
   return scoped_ptr<AudioWriter>(new AudioWriter());
 }
 
 }  // namespace protocol
 }  // namespace remoting