C++11 declares a type safe null pointer

content/common/gpu/client/gpu_video_decode_accelerator_host.h

 // 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.
 
 #ifndef CONTENT_COMMON_GPU_CLIENT_GPU_VIDEO_DECODE_ACCELERATOR_HOST_H_
 #define CONTENT_COMMON_GPU_CLIENT_GPU_VIDEO_DECODE_ACCELERATOR_HOST_H_
 
 #include <vector>
 
 #include "base/memory/weak_ptr.h"
@@ skipping 55 matching lines @@
   void OnDismissPictureBuffer(int32 picture_buffer_id);
   void OnPictureReady(int32 picture_buffer_id,
                       int32 bitstream_buffer_id,
                       const gfx::Rect& visible_rect);
   void OnFlushDone();
   void OnResetDone();
   void OnNotifyError(uint32 error);
 
   // Unowned reference to the GpuChannelHost to send IPC messages to the GPU
   // process.  |channel_| outlives |impl_|, so the reference is always valid as
-  // long as it is not NULL.
+  // long as it is not nullptr.
   GpuChannelHost* channel_;
 
   // Route ID for the associated decoder in the GPU process.
   int32 decoder_route_id_;
 
   // The client that will receive callbacks from the decoder.
   Client* client_;
 
   // Unowned reference to the CommandBufferProxyImpl that created us.  |this|
   // registers as a DeletionObserver of |impl_|, the so reference is always
-  // valid as long as it is not NULL.
+  // valid as long as it is not nullptr.
   CommandBufferProxyImpl* impl_;
 
   // Requested dimensions of the buffer, from ProvidePictureBuffers().
   gfx::Size picture_buffer_dimensions_;
 
   // WeakPtr factory for posting tasks back to itself.
   base::WeakPtrFactory<GpuVideoDecodeAcceleratorHost> weak_this_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuVideoDecodeAcceleratorHost);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_GPU_CLIENT_GPU_VIDEO_DECODE_ACCELERATOR_HOST_H_