Remove implicit cast from CFX_ByteString to (const char*).

xfa/fxfa/app/xfa_ffdoc.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 "xfa/fxfa/include/xfa_ffdoc.h"
 
 #include "core/fpdfapi/fpdf_parser/include/cpdf_array.h"
 #include "core/fpdfapi/fpdf_parser/include/cpdf_document.h"
@@ skipping 394 matching lines @@
     pNode = m_pDocument->GetRoot();
   } else {
     pNode = ToNode(m_pDocument->GetXFAObject(packetHash));
   }
   FX_BOOL bFlags = FALSE;
   if (pNode) {
     CFX_ByteString bsChecksum;
     if (pCSContext) {
       pCSContext->GetChecksum(bsChecksum);
     }
-    bFlags = pExport->Export(pFile, pNode, 0, bsChecksum.GetLength()
-                                                  ? (const FX_CHAR*)bsChecksum
-                                                  : NULL);
+    bFlags = pExport->Export(
+        pFile, pNode, 0, bsChecksum.GetLength() ? bsChecksum.c_str() : NULL);
   } else {
     bFlags = pExport->Export(pFile);
   }
   pExport->Release();
   return bFlags;
 }
 FX_BOOL CXFA_FFDoc::ImportData(IFX_FileRead* pStream, FX_BOOL bXDP) {
   std::unique_ptr<CXFA_DataImporter, ReleaseDeleter<CXFA_DataImporter>>
       importer(new CXFA_DataImporter(m_pDocument));
 
   return importer->ImportData(pStream);
 }