Get rid of NULLs in fpdfsdk/

fpdfsdk/fxedit/include/fxet_list.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 FPDFSDK_FXEDIT_INCLUDE_FXET_LIST_H_
 #define FPDFSDK_FXEDIT_INCLUDE_FXET_LIST_H_
 
 #include "fpdfsdk/fxedit/include/fx_edit.h"
@@ skipping 175 matching lines @@
   CLST_Rect m_rcContent;  // positive forever!
 };
 
 template <class TYPE>
 class CLST_ArrayTemplate : public CFX_ArrayTemplate<TYPE> {
  public:
   FX_BOOL IsEmpty() { return CFX_ArrayTemplate<TYPE>::GetSize() <= 0; }
   TYPE GetAt(int32_t nIndex) const {
     if (nIndex >= 0 && nIndex < CFX_ArrayTemplate<TYPE>::GetSize())
       return CFX_ArrayTemplate<TYPE>::GetAt(nIndex);
-    return NULL;
+    return nullptr;
   }
   void RemoveAt(int32_t nIndex) {
     if (nIndex >= 0 && nIndex < CFX_ArrayTemplate<TYPE>::GetSize())
       CFX_ArrayTemplate<TYPE>::RemoveAt(nIndex);
   }
 };
 
 class CFX_List : protected CFX_ListContainer, public IFX_List {
  public:
   CFX_List();
@@ skipping 123 matching lines @@
   FX_BOOL m_bNotifyFlag;
   CFX_FloatPoint m_ptScrollPos;
   CPLST_Select m_aSelItems;  // for multiple
   int32_t m_nSelItem;        // for single
   int32_t m_nFootIndex;      // for multiple
   FX_BOOL m_bCtrlSel;        // for multiple
   int32_t m_nCaretIndex;     // for multiple
 };
 
 #endif  // FPDFSDK_FXEDIT_INCLUDE_FXET_LIST_H_