Fix offset outside bounds warning on GCC

core/fpdfapi/fpdf_parser/cpdf_syntax_parser.cpp

 // 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
 
 #include "core/fpdfapi/fpdf_parser/cpdf_syntax_parser.h"
 
 #include <vector>
 
@@ skipping 453 matching lines @@
       if (key.IsEmpty())
         continue;
 
       if (key == "/Contents")
         dwSignValuePos = m_Pos;
 
       CPDF_Object* pObj = GetObject(pObjList, objnum, gennum, true);
       if (!pObj)
         continue;
 
-      CFX_ByteStringC keyNoSlash(key.c_str() + 1, key.GetLength() - 1);
+      CFX_ByteStringC keyNoSlash(key.raw_str() + 1, key.GetLength() - 1);
       pDict->SetAt(keyNoSlash, pObj);
     }
 
     // Only when this is a signature dictionary and has contents, we reset the
     // contents to the un-decrypted form.
     if (pDict->IsSignatureDict() && dwSignValuePos) {
       CFX_AutoRestorer<FX_FILESIZE> save_pos(&m_Pos);
       m_Pos = dwSignValuePos;
       pDict->SetAt("Contents", GetObject(pObjList, objnum, gennum, false));
     }
@@ skipping 496 matching lines @@
     if (limit && m_Pos == limit)
       return -1;
   }
   return -1;
 }
 
 void CPDF_SyntaxParser::SetEncrypt(
     std::unique_ptr<IPDF_CryptoHandler> pCryptoHandler) {
   m_pCryptoHandler = std::move(pCryptoHandler);
 }