Get rid of NULLs in xfa/fxbarcode/

xfa/fxbarcode/common/BC_GlobalHistogramBinarizer.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 2009 ZXing authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ skipping 69 matching lines @@
   int32_t height = source->GetHeight();
   std::unique_ptr<CBC_CommonBitMatrix> matrix(new CBC_CommonBitMatrix());
   matrix->Init(width, height);
   InitArrays(width);
   CFX_Int32Array localBuckets;
   localBuckets.Copy(m_buckets);
   int32_t y;
   for (y = 1; y < 5; y++) {
     int32_t row = height * y / 5;
     CFX_ByteArray* localLuminances = source->GetRow(row, m_luminance, e);
-    BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
+    BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
     int32_t right = (width << 2) / 5;
     int32_t x;
     for (x = width / 5; x < right; x++) {
       int32_t pixel = (*localLuminances)[x] & 0xff;
       localBuckets[pixel >> LUMINANCE_SHIFT]++;
     }
   }
   int32_t blackPoint = EstimateBlackPoint(localBuckets, e);
-  BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
+  BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
   std::unique_ptr<CFX_ByteArray> localLuminances(source->GetMatrix());
   for (y = 0; y < height; y++) {
     int32_t offset = y * width;
     for (int32_t x = 0; x < width; x++) {
       int32_t pixel = (*localLuminances)[offset + x] & 0xff;
       if (pixel < blackPoint) {
         matrix->Set(x, y);
       }
     }
   }
@@ skipping 54 matching lines @@
     int32_t fromFirst = x - firstPeak;
     int32_t score = fromFirst * fromFirst * (secondPeak - x) *
                     (maxBucketCount - buckets[x]);
     if (score > bestValleyScore) {
       bestValley = x;
       bestValleyScore = score;
     }
   }
   return bestValley << LUMINANCE_SHIFT;
 }