C++11 declares a type safe null pointer

content/common/gpu/image_transport_surface_iosurface_mac.h

 // Copyright 2014 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.
 
 #ifndef CONTENT_COMMON_GPU_IMAGE_TRANSPORT_SURFACE_IOSURFACE_MAC_H_
 #define CONTENT_COMMON_GPU_IMAGE_TRANSPORT_SURFACE_IOSURFACE_MAC_H_
 
 #include <list>
 
 #include "content/common/gpu/image_transport_surface_fbo_mac.h"
@@ skipping 25 matching lines @@
  private:
   ImageTransportSurfaceFBO* transport_surface_;
 
   base::ScopedCFTypeRef<IOSurfaceRef> io_surface_;
 
   // The list of IOSurfaces that have been sent to the browser process but have
   // not been opened in the browser process yet. This list should never have
   // more than one entry.
   std::list<base::ScopedCFTypeRef<IOSurfaceRef>> pending_swapped_surfaces_;
 
-  // The id of |io_surface_| or 0 if that's NULL.
+  // The id of |io_surface_| or 0 if that's nullptr.
   IOSurfaceID io_surface_id_;
 
   DISALLOW_COPY_AND_ASSIGN(IOSurfaceStorageProvider);
 };
 
 }  // namespace content
 
 #endif  //  CONTENT_COMMON_GPU_IMAGE_TRANSPORT_SURFACE_MAC_H_