Refcount IFGAS_ streams all the time, too

testing/libfuzzer/pdf_cfx_saxreader_fuzzer.cc

 // Copyright 2016 The 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.
 
 #include <memory>
 
+#include "core/fxcrt/cfx_retain_ptr.h"
 #include "xfa/fde/xml/cfx_saxreader.h"
 #include "xfa/fgas/crt/fgas_stream.h"
 #include "xfa/fxfa/parser/cxfa_widetextread.h"
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   CFX_WideString input = CFX_WideString::FromUTF8(
       CFX_ByteStringC(data, static_cast<FX_STRSIZE>(size)));
-  std::unique_ptr<IFGAS_Stream, ReleaseDeleter<IFGAS_Stream>> stream(
-      new CXFA_WideTextRead(input));
+  auto stream = pdfium::MakeRetain<CXFA_WideTextRead>(input);
   if (!stream)
     return 0;
 
   CFX_RetainPtr<IFX_SeekableReadStream> fileRead =
       stream->MakeSeekableReadStream();
   if (!fileRead)
     return 0;
 
   CFX_SAXReader reader;
   if (reader.StartParse(fileRead, 0, -1, CFX_SaxParseMode_NotSkipSpace) < 0)
     return 0;
 
   while (1) {
     int32_t ret = reader.ContinueParse(nullptr);
     if (ret < 0 || ret > 99)
       break;
   }
 
   return 0;
 }