Null CPDF_CountedObj::m_pObj prior to deletion

core/fxcrt/cfx_string_data_template.h

 // Copyright 2016 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_CFX_STRING_DATA_TEMPLATE_H_
 #define CORE_FXCRT_CFX_STRING_DATA_TEMPLATE_H_
 
 #include "core/fxcrt/include/fx_memory.h"
@@ skipping 67 matching lines @@
     ASSERT(offset >= 0 && nLen >= 0 && offset + nLen <= m_nAllocLength);
     FXSYS_memcpy(m_String + offset, pStr, nLen * sizeof(CharType));
     m_String[offset + nLen] = 0;
   }
 
   // To ensure ref counts do not overflow, consider the worst possible case:
   // the entire address space contains nothing but pointers to this object.
   // Since the count increments with each new pointer, the largest value is
   // the number of pointers that can fit into the address space. The size of
   // the address space itself is a good upper bound on it.
-  intptr_t m_nRefs;  // Would prefer ssize_t, but no windows support.
+  intptr_t m_nRefs;
 
   // |FX_STRSIZE| is currently typedef'd as |int|.
   // TODO(palmer): It should be a |size_t|, or at least unsigned.
   // These lengths are in terms of number of characters, not bytes, and do not
   // include the terminating NUL character, but the underlying buffer is sized
   // to be capable of holding it.
   FX_STRSIZE m_nDataLength;
   FX_STRSIZE m_nAllocLength;
 
   // Not really 1, variable size.
   CharType m_String[1];
 
  private:
   CFX_StringDataTemplate(FX_STRSIZE dataLen, FX_STRSIZE allocLen)
       : m_nRefs(0), m_nDataLength(dataLen), m_nAllocLength(allocLen) {
     ASSERT(dataLen >= 0);
     ASSERT(dataLen <= allocLen);
     m_String[dataLen] = 0;
   }
 
   ~CFX_StringDataTemplate() = delete;
 };
 
 extern template class CFX_StringDataTemplate<FX_CHAR>;
 extern template class CFX_StringDataTemplate<FX_WCHAR>;
 
 #endif  // CORE_FXCRT_CFX_STRING_DATA_TEMPLATE_H_