Get rid of NULLs in fpdfsdk/

fpdfsdk/fpdfdoc.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
 
 #include "public/fpdf_doc.h"
 
 #include <set>
 
@@ skipping 112 matching lines @@
   // If this bookmark is not directly associated with a dest, we try to get
   // action
   CPDF_Action action = bookmark.GetAction();
   if (!action.GetDict())
     return nullptr;
   return action.GetDest(pDoc).GetObject();
 }
 
 DLLEXPORT FPDF_ACTION STDCALL FPDFBookmark_GetAction(FPDF_BOOKMARK pDict) {
   if (!pDict)
-    return NULL;
+    return nullptr;
   CPDF_Bookmark bookmark(ToDictionary(static_cast<CPDF_Object*>(pDict)));
   return bookmark.GetAction().GetDict();
 }
 
 DLLEXPORT unsigned long STDCALL FPDFAction_GetType(FPDF_ACTION pDict) {
   if (!pDict)
     return PDFACTION_UNSUPPORTED;
 
   CPDF_Action action(ToDictionary(static_cast<CPDF_Object*>(pDict)));
   CPDF_Action::ActionType type = action.GetType();
@@ skipping 212 matching lines @@
     return 0;
   CFX_WideString text = pInfo->GetUnicodeTextBy(tag);
   // Use UTF-16LE encoding
   CFX_ByteString encodedText = text.UTF16LE_Encode();
   unsigned long len = encodedText.GetLength();
   if (buffer && buflen >= len) {
     FXSYS_memcpy(buffer, encodedText.c_str(), len);
   }
   return len;
 }