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

remoting/host/desktop_session_agent.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/host/desktop_session_agent.h"
 
 #include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/memory/shared_memory.h"
 #include "ipc/ipc_channel_proxy.h"
@@ skipping 57 matching lines @@
 
 // webrtc::SharedMemory implementation that notifies creating
 // DesktopSessionAgent when it's deleted.
 class DesktopSessionAgent::SharedBuffer : public webrtc::SharedMemory {
  public:
   static scoped_ptr<SharedBuffer> Create(DesktopSessionAgent* agent,
                                          size_t size,
                                          int id) {
     scoped_ptr<base::SharedMemory> memory(new base::SharedMemory());
     if (!memory->CreateAndMapAnonymous(size))
-      return scoped_ptr<SharedBuffer>();
+      return nullptr;
     return scoped_ptr<SharedBuffer>(
         new SharedBuffer(agent, memory.Pass(), size, id));
   }
 
   virtual ~SharedBuffer() {
     agent_->OnSharedBufferDeleted(id());
   }
 
  private:
   SharedBuffer(DesktopSessionAgent* agent,
@@ skipping 494 matching lines @@
 void DesktopSessionAgent::OnSharedBufferDeleted(int id) {
   DCHECK(video_capture_task_runner_->BelongsToCurrentThread());
   DCHECK(id != 0);
 
   shared_buffers_--;
   DCHECK_GE(shared_buffers_, 0);
   SendToNetwork(new ChromotingDesktopNetworkMsg_ReleaseSharedBuffer(id));
 }
 
 }  // namespace remoting