Get rid of NULLs in core/

core/fxge/include/fx_ge_win32.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_FXGE_INCLUDE_FX_GE_WIN32_H_
 #define CORE_FXGE_INCLUDE_FX_GE_WIN32_H_
 
 #ifdef _WIN32
@@ skipping 15 matching lines @@
 class CFX_WindowsDIB : public CFX_DIBitmap {
  public:
   static CFX_ByteString GetBitmapInfo(const CFX_DIBitmap* pBitmap);
 
   static CFX_DIBitmap* LoadFromBuf(BITMAPINFO* pbmi, void* pData);
 
   static HBITMAP GetDDBitmap(const CFX_DIBitmap* pBitmap, HDC hDC);
 
   static CFX_DIBitmap* LoadFromDDB(HDC hDC,
                                    HBITMAP hBitmap,
-                                   uint32_t* pPalette = NULL,
+                                   uint32_t* pPalette = nullptr,
                                    uint32_t size = 256);
 
   static CFX_DIBitmap* LoadFromFile(const FX_WCHAR* filename);
 
   static CFX_DIBitmap* LoadFromFile(const FX_CHAR* filename) {
     return LoadFromFile(CFX_WideString::FromLocal(filename).c_str());
   }
 
   static CFX_DIBitmap* LoadDIBitmap(WINDIB_Open_Args_ args);
 
@@ skipping 37 matching lines @@
  protected:
   HBITMAP m_hBitmap;
 
   HBITMAP m_hOldBitmap;
 
   HDC m_hDC;
 };
 #endif
 
 #endif  // CORE_FXGE_INCLUDE_FX_GE_WIN32_H_