Get rid of NULLs in core/

core/fxcrt/include/fx_ext.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 CORE_FXCRT_INCLUDE_FX_EXT_H_
 #define CORE_FXCRT_INCLUDE_FX_EXT_H_
 
 #include <cctype>
 #include <cwctype>
 
 #include "core/fxcrt/include/fx_basic.h"
 
 #define FX_INVALID_OFFSET static_cast<uint32_t>(-1)
 
 // TODO(thestig) Using unique_ptr with ReleaseDeleter is still not ideal.
 // Come up or wait for something better. This appears in this file rather
 // than fx_stream.h due to include ordering restrictions.
 using ScopedFileStream =
     std::unique_ptr<IFX_FileStream, ReleaseDeleter<IFX_FileStream>>;
 
 FX_FLOAT FXSYS_tan(FX_FLOAT a);
 FX_FLOAT FXSYS_logb(FX_FLOAT b, FX_FLOAT x);
 FX_FLOAT FXSYS_strtof(const FX_CHAR* pcsStr,
                       int32_t iLength = -1,
-                      int32_t* pUsedLen = NULL);
+                      int32_t* pUsedLen = nullptr);
 FX_FLOAT FXSYS_wcstof(const FX_WCHAR* pwsStr,
                       int32_t iLength = -1,
-                      int32_t* pUsedLen = NULL);
+                      int32_t* pUsedLen = nullptr);
 FX_WCHAR* FXSYS_wcsncpy(FX_WCHAR* dstStr, const FX_WCHAR* srcStr, size_t count);
 int32_t FXSYS_wcsnicmp(const FX_WCHAR* s1, const FX_WCHAR* s2, size_t count);
 int32_t FXSYS_strnicmp(const FX_CHAR* s1, const FX_CHAR* s2, size_t count);
 
 inline bool FXSYS_islower(int32_t ch) {
   return ch >= 'a' && ch <= 'z';
 }
 inline bool FXSYS_isupper(int32_t ch) {
   return ch >= 'A' && ch <= 'Z';
 }
@@ skipping 82 matching lines @@
           j -= gap;
         }
         pArray[j + gap] = v1;
       }
       gap >>= 1;
     }
   }
 };
 
 #endif  // CORE_FXCRT_INCLUDE_FX_EXT_H_