Switch from nonstd::unique_ptr to std::unique_ptr.

core/src/fpdfapi/fpdf_edit/fpdf_edit_doc.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 <limits.h>
 
 #include "core/include/fpdfapi/fpdf_module.h"
 #include "core/include/fpdfapi/fpdf_page.h"
@@ skipping 828 matching lines @@
     flags |= PDFFONT_FORCEBOLD;
   }
   if (pFont->IsItalic()) {
     flags |= PDFFONT_ITALIC;
   }
   if (pFont->IsFixedWidth()) {
     flags |= PDFFONT_FIXEDPITCH;
   }
   CPDF_Dictionary* pBaseDict = new CPDF_Dictionary;
   pBaseDict->SetAtName("Type", "Font");
-  nonstd::unique_ptr<CFX_UnicodeEncoding> pEncoding(
+  std::unique_ptr<CFX_UnicodeEncoding> pEncoding(
       new CFX_UnicodeEncoding(pFont));
   CPDF_Dictionary* pFontDict = pBaseDict;
   if (!bCJK) {
     CPDF_Array* pWidths = new CPDF_Array;
     int charcode;
     for (charcode = 32; charcode < 128; charcode++) {
       int glyph_index = pEncoding->GlyphFromCharCode(charcode);
       int char_width = pFont->GetGlyphWidth(glyph_index);
       pWidths->AddInteger(char_width);
     }
@@ skipping 281 matching lines @@
 void FPDFAPI_FlatPageAttr(CPDF_Dictionary* pPageDict,
                           const CFX_ByteStringC& name) {
   if (pPageDict->KeyExist(name)) {
     return;
   }
   CPDF_Object* pObj = FPDFAPI_GetPageAttr(pPageDict, name);
   if (pObj) {
     pPageDict->SetAt(name, pObj->Clone());
   }
 }