Get rid of NULLs in xfa/fxbarcode/

xfa/fxbarcode/oned/BC_OneDimWriter.h

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #ifndef XFA_FXBARCODE_ONED_BC_ONEDIMWRITER_H_
 #define XFA_FXBARCODE_ONED_BC_ONEDIMWRITER_H_
 
 #include "core/fxge/include/fx_ge.h"
@@ skipping 16 matching lines @@
                   int32_t& e);
   uint8_t* Encode(const CFX_ByteString& contents,
                   BCFORMAT format,
                   int32_t& outWidth,
                   int32_t& outHeight,
                   int32_t hints,
                   int32_t& e);
   virtual uint8_t* Encode(const CFX_ByteString& contents,
                           int32_t& outLength,
                           int32_t& e) {
-    return NULL;
+    return nullptr;
   }
 
   virtual void RenderResult(const CFX_WideStringC& contents,
                             uint8_t* code,
                             int32_t codeLength,
                             FX_BOOL isDevice,
                             int32_t& e);
   virtual void RenderBitmapResult(CFX_DIBitmap*& pOutBitmap,
                                   const CFX_WideStringC& contents,
                                   int32_t& e);
@@ skipping 66 matching lines @@
   int32_t m_iContentLen;
   FX_BOOL m_bLeftPadding;
   FX_BOOL m_bRightPadding;
   CBC_CommonBitMatrix* m_output;
   int32_t m_barWidth;
   int32_t m_multiple;
   FX_FLOAT m_outputHScale;
 };
 
 #endif  // XFA_FXBARCODE_ONED_BC_ONEDIMWRITER_H_