replace NULL->nullptr in src/remoting.

remoting/host/clipboard_mac.mm

 // 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/clipboard.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
@@ skipping 33 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(ClipboardMac);
 };
 
 ClipboardMac::ClipboardMac() : current_change_count_(0) {
 }
 
 ClipboardMac::~ClipboardMac() {
   // In it2me the destructor is not called in the same thread that the timer is
   // created. Thus the timer must have already been destroyed by now.
-  DCHECK(clipboard_polling_timer_.get() == NULL);
+  DCHECK(clipboard_polling_timer_.get() == nullptr);
 }
 
 void ClipboardMac::Start(scoped_ptr<protocol::ClipboardStub> client_clipboard) {
   client_clipboard_.reset(client_clipboard.release());
 
   // Synchronize local change-count with the pasteboard's. The change-count is
   // used to detect clipboard changes.
   current_change_count_ = [[NSPasteboard generalPasteboard] changeCount];
 
   // OS X doesn't provide a clipboard-changed notification. The only way to
@@ skipping 47 matching lines @@
   event.set_mime_type(kMimeTypeTextUtf8);
   event.set_data(base::SysNSStringToUTF8(data));
   client_clipboard_->InjectClipboardEvent(event);
 }
 
 scoped_ptr<Clipboard> Clipboard::Create() {
   return make_scoped_ptr(new ClipboardMac());
 }
 
 }  // namespace remoting