C++11 declares a type safe null pointer

content/common/gpu/client/gpu_memory_buffer_impl_io_surface.cc

 // Copyright 2013 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 "content/common/gpu/client/gpu_memory_buffer_impl_io_surface.h"
 
 #include "base/atomic_sequence_num.h"
 #include "base/bind.h"
 #include "base/logging.h"
 #include "content/common/gpu/client/gpu_memory_buffer_factory_host.h"
@@ skipping 127 matching lines @@
     case GL_BGRA8_EXT:
       return 'BGRA';
     default:
       NOTREACHED();
       return 0;
   }
 }
 
 void* GpuMemoryBufferImplIOSurface::Map() {
   DCHECK(!mapped_);
-  IOSurfaceLock(io_surface_, 0, NULL);
+  IOSurfaceLock(io_surface_, 0, nullptr);
   mapped_ = true;
   return IOSurfaceGetBaseAddress(io_surface_);
 }
 
 void GpuMemoryBufferImplIOSurface::Unmap() {
   DCHECK(mapped_);
-  IOSurfaceUnlock(io_surface_, 0, NULL);
+  IOSurfaceUnlock(io_surface_, 0, nullptr);
   mapped_ = false;
 }
 
 uint32 GpuMemoryBufferImplIOSurface::GetStride() const {
   return IOSurfaceGetBytesPerRow(io_surface_);
 }
 
 gfx::GpuMemoryBufferHandle GpuMemoryBufferImplIOSurface::GetHandle() const {
   gfx::GpuMemoryBufferHandle handle;
   handle.type = gfx::IO_SURFACE_BUFFER;
   handle.io_surface_id = IOSurfaceGetID(io_surface_);
   return handle;
 }
 
 }  // namespace content