Convert loose FX_Create* functions into static methods

core/fpdfapi/parser/cfdf_document.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 "core/fpdfapi/parser/cfdf_document.h"
 
 #include <memory>
 #include <utility>
@@ skipping 27 matching lines @@
   if (!pFile)
     return nullptr;
 
   auto pDoc = pdfium::MakeUnique<CFDF_Document>();
   pDoc->ParseStream(pFile, bOwnFile);
   return pDoc->m_pRootDict ? std::move(pDoc) : nullptr;
 }
 
 std::unique_ptr<CFDF_Document> CFDF_Document::ParseMemory(const uint8_t* pData,
                                                           uint32_t size) {
-  return CFDF_Document::ParseFile(FX_CreateMemoryStream((uint8_t*)pData, size),
-                                  true);
+  return CFDF_Document::ParseFile(
+      IFX_MemoryStream::Create((uint8_t*)pData, size), true);
 }
 
 void CFDF_Document::ParseStream(IFX_SeekableReadStream* pFile, bool bOwnFile) {
   m_pFile = pFile;
   m_bOwnFile = bOwnFile;
   CPDF_SyntaxParser parser;
   parser.InitParser(m_pFile, 0);
   while (1) {
     bool bNumber;
     CFX_ByteString word = parser.GetNextWord(&bNumber);
@@ skipping 39 matching lines @@
 
   buf << "%FDF-1.2\r\n";
   for (const auto& pair : *this)
     buf << pair.first << " 0 obj\r\n"
         << pair.second.get() << "\r\nendobj\r\n\r\n";
 
   buf << "trailer\r\n<</Root " << m_pRootDict->GetObjNum()
       << " 0 R>>\r\n%%EOF\r\n";
   return true;
 }