FPDF_Creator can only create file through embedder-supplied callback.

core/src/fpdfapi/fpdf_edit/fpdf_edit_create.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 "../../../include/fxcrt/fx_ext.h"
 #include "../../../include/fpdfapi/fpdf_serial.h"
 #include "editint.h"
 
@@ skipping 1998 matching lines @@
 void CPDF_Creator::Clear() {
   delete m_pXRefStream;
   m_pXRefStream = NULL;
   m_File.Clear();
   m_NewObjNumArray.RemoveAll();
   if (m_pIDArray) {
     m_pIDArray->Release();
     m_pIDArray = NULL;
   }
 }
-FX_BOOL CPDF_Creator::Create(const FX_CHAR* filename, FX_DWORD flags) {
-  if (!m_File.AttachFile(filename)) {
-    return FALSE;
-  }
-  FX_BOOL bRet = Create(flags);
-  if (!bRet || !(flags & FPDFCREATE_PROGRESSIVE)) {
-    Clear();
-  }
-  return bRet;
-}
-FX_BOOL CPDF_Creator::Create(const FX_WCHAR* filename, FX_DWORD flags) {
-  if (!m_File.AttachFile(filename)) {
-    return FALSE;
-  }
-  FX_BOOL bRet = Create(flags);
-  if (!bRet || !(flags & FPDFCREATE_PROGRESSIVE)) {
-    Clear();
-  }
-  return bRet;
-}
 FX_BOOL CPDF_Creator::Create(IFX_StreamWrite* pFile, FX_DWORD flags) {
   if (!pFile) {
     return FALSE;
   }
   if (!m_File.AttachFile(pFile, FALSE)) {
     return FALSE;
   }
   return Create(flags);
 }
 FX_BOOL CPDF_Creator::Create(FX_DWORD flags) {
@@ skipping 110 matching lines @@
   m_bNewCrypto = FALSE;
   if (!m_bStandardSecurity) {
     return;
   }
   if (m_pEncryptDict) {
     m_pEncryptDict->Release();
     m_pEncryptDict = NULL;
   }
   m_bStandardSecurity = FALSE;
 }