Get rid of NULLs in xfa/fxbarcode/

xfa/fxbarcode/datamatrix/BC_DataMatrixReader.cpp

 // 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
 // Original code is licensed as follows:
 /*
  * Copyright 2007 ZXing authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ skipping 15 matching lines @@
 
 #include "xfa/fxbarcode/BC_BinaryBitmap.h"
 #include "xfa/fxbarcode/BC_Reader.h"
 #include "xfa/fxbarcode/common/BC_CommonDecoderResult.h"
 #include "xfa/fxbarcode/datamatrix/BC_DataMatrixDecoder.h"
 #include "xfa/fxbarcode/datamatrix/BC_DataMatrixDetector.h"
 #include "xfa/fxbarcode/qrcode/BC_QRDetectorResult.h"
 #include "xfa/fxbarcode/utils.h"
 
 CBC_DataMatrixReader::CBC_DataMatrixReader() {
-  m_decoder = NULL;
+  m_decoder = nullptr;
 }
 void CBC_DataMatrixReader::Init() {
   m_decoder = new CBC_DataMatrixDecoder;
   m_decoder->Init();
 }
 CBC_DataMatrixReader::~CBC_DataMatrixReader() {
   delete m_decoder;
 }
 CFX_ByteString CBC_DataMatrixReader::Decode(CBC_BinaryBitmap* image,
                                             int32_t hints,
                                             int32_t& e) {
   CBC_CommonBitMatrix* cdr = image->GetBlackMatrix(e);
   BC_EXCEPTION_CHECK_ReturnValue(e, "");
   CBC_DataMatrixDetector detector(cdr);
   detector.Init(e);
   BC_EXCEPTION_CHECK_ReturnValue(e, "");
   std::unique_ptr<CBC_QRDetectorResult> detectorResult(detector.Detect(e));
   BC_EXCEPTION_CHECK_ReturnValue(e, "");
   std::unique_ptr<CBC_CommonDecoderResult> decodeResult(
       m_decoder->Decode(detectorResult->GetBits(), e));
   BC_EXCEPTION_CHECK_ReturnValue(e, "");
   return decodeResult->GetText();
 }
 CFX_ByteString CBC_DataMatrixReader::Decode(CBC_BinaryBitmap* image,
                                             int32_t& e) {
   CFX_ByteString bs = Decode(image, 0, e);
   BC_EXCEPTION_CHECK_ReturnValue(e, "");
   return bs;
 }