Make down-conversion explicit from CFX_ByteString to CFX_ByteStringC.

core/fxcrt/fxcrt_posix.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/fxcrt/fxcrt_posix.h"
 
 #include "core/fxcrt/include/fx_basic.h"
 
@@ skipping 27 matching lines @@
   if (m_nFD > -1) {
     return FALSE;
   }
   int32_t nFlags, nMasks;
   FXCRT_Posix_GetFileMode(dwMode, nFlags, nMasks);
   m_nFD = open(fileName.GetCStr(), nFlags, nMasks);
   return m_nFD > -1;
 }
 FX_BOOL CFXCRT_FileAccess_Posix::Open(const CFX_WideStringC& fileName,
                                       uint32_t dwMode) {
-  return Open(FX_UTF8Encode(fileName), dwMode);
+  return Open(FX_UTF8Encode(fileName).AsByteStringC(), dwMode);
 }
 void CFXCRT_FileAccess_Posix::Close() {
   if (m_nFD < 0) {
     return;
   }
   close(m_nFD);
   m_nFD = -1;
 }
 void CFXCRT_FileAccess_Posix::Release() {
   delete this;
@@ skipping 62 matching lines @@
   }
   return fsync(m_nFD) > -1;
 }
 FX_BOOL CFXCRT_FileAccess_Posix::Truncate(FX_FILESIZE szFile) {
   if (m_nFD < 0) {
     return FALSE;
   }
   return !ftruncate(m_nFD, szFile);
 }
 #endif