Get rid of NULLs in xfa/

xfa/fxfa/parser/xfa_basic_imp.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_FXFA_PARSER_XFA_BASIC_IMP_H_
 #define XFA_FXFA_PARSER_XFA_BASIC_IMP_H_
 
 #include "xfa/fgas/crt/fgas_stream.h"
@@ skipping 19 matching lines @@
   virtual uint32_t GetAccessModes() const;
   virtual int32_t GetLength() const;
   virtual int32_t Seek(FX_STREAMSEEK eSeek, int32_t iOffset);
   virtual int32_t GetPosition();
   virtual FX_BOOL IsEOF() const;
 
   virtual int32_t ReadData(uint8_t* pBuffer, int32_t iBufferSize) { return 0; }
   virtual int32_t ReadString(FX_WCHAR* pStr,
                              int32_t iMaxLength,
                              FX_BOOL& bEOS,
-                             int32_t const* pByteSize = NULL);
+                             int32_t const* pByteSize = nullptr);
   virtual int32_t WriteData(const uint8_t* pBuffer, int32_t iBufferSize) {
     return 0;
   }
   virtual int32_t WriteString(const FX_WCHAR* pStr, int32_t iLength) {
     return 0;
   }
   virtual void Flush() {}
   virtual FX_BOOL SetLength(int32_t iLength) { return FALSE; }
 
   virtual int32_t GetBOM(uint8_t bom[4]) const { return 0; }
   virtual uint16_t GetCodePage() const;
   virtual uint16_t SetCodePage(uint16_t wCodePage);
 
   virtual void Lock() {}
   virtual void Unlock() {}
 
   virtual IFX_Stream* CreateSharedStream(uint32_t dwAccess,
                                          int32_t iOffset,
                                          int32_t iLength) {
-    return NULL;
+    return nullptr;
   }
 
   CFX_WideString GetSrcText() const { return m_wsBuffer; }
 
  protected:
   CFX_WideString m_wsBuffer;
   int32_t m_iPosition;
   int32_t m_iRefCount;
 };
 
 #endif  // XFA_FXFA_PARSER_XFA_BASIC_IMP_H_