Take advantage of implicit std::unique_ptr<>(nulltpr_t) ctor.

fpdfsdk/pdfwindow/PWL_FontMap.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 "fpdfsdk/pdfwindow/PWL_FontMap.h"
 
 #include "core/fpdfapi/cpdf_modulemgr.h"
 #include "core/fpdfapi/font/cpdf_font.h"
@@ skipping 30 matching lines @@
   ASSERT(m_pSystemHandler);
 }
 
 CPWL_FontMap::~CPWL_FontMap() {
   Empty();
 }
 
 CPDF_Document* CPWL_FontMap::GetDocument() {
   if (!m_pPDFDoc) {
     if (CPDF_ModuleMgr::Get()) {
-      m_pPDFDoc =
-          pdfium::MakeUnique<CPDF_Document>(std::unique_ptr<CPDF_Parser>());
+      m_pPDFDoc = pdfium::MakeUnique<CPDF_Document>(nullptr);
       m_pPDFDoc->CreateNewDoc();
     }
   }
 
   return m_pPDFDoc.get();
 }
 
 CPDF_Font* CPWL_FontMap::GetPDFFont(int32_t nFontIndex) {
   if (nFontIndex >= 0 && nFontIndex < m_aData.GetSize()) {
     if (CPWL_FontMap_Data* pData = m_aData.GetAt(nFontIndex)) {
@@ skipping 377 matching lines @@
     return FXFONT_RUSSIAN_CHARSET;
 
   if (word >= 0x0100 && word <= 0x024F)
     return FXFONT_EASTEUROPE_CHARSET;
 
   if (word >= 0x1E00 && word <= 0x1EFF)
     return FXFONT_VIETNAMESE_CHARSET;
 
   return FXFONT_ANSI_CHARSET;
 }