Make concrete stream classes private to .cpp, part 3

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/xfa_ffdoc.h"
 
 #include <algorithm>
 #include <memory>
@@ skipping 308 matching lines @@
     for (size_t i = 0; i < pXFAArray->GetCount() / 2; i++) {
       if (CPDF_Stream* pStream = pXFAArray->GetStreamAt(i * 2 + 1))
         xfaStreams.push_back(pStream);
     }
   } else if (pElementXFA->IsStream()) {
     xfaStreams.push_back((CPDF_Stream*)pElementXFA);
   }
   if (xfaStreams.empty())
     return false;
 
-  IFX_SeekableReadStream* pFileRead = new CXFA_FileRead(xfaStreams);
+  IFX_SeekableReadStream* pFileRead = MakeSeekableReadStream(xfaStreams);
   m_pPDFDoc = pPDFDoc;
   if (m_pStream) {
     m_pStream->Release();
     m_pStream = nullptr;
   }
   m_pStream = pFileRead;
   m_bOwnStream = true;
   return true;
 }
 
@@ skipping 104 matching lines @@
 
   return !!pExport->Export(
       pFile, pNode, 0, bsChecksum.GetLength() ? bsChecksum.c_str() : nullptr);
 }
 
 bool CXFA_FFDoc::ImportData(IFX_SeekableReadStream* pStream, bool bXDP) {
   std::unique_ptr<CXFA_DataImporter> importer(
       new CXFA_DataImporter(m_pDocumentParser->GetDocument()));
   return importer->ImportData(pStream);
 }