Split off CPDF_Document into its own .cpp/.h files.

core/src/fpdfdoc/doc_utils.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 <algorithm>
 
+#include "core/include/fpdfapi/cpdf_document.h"
 #include "core/include/fpdfdoc/fpdf_doc.h"
 #include "core/src/fpdfdoc/doc_utils.h"
 
 static const int FPDFDOC_UTILS_MAXRECURSION = 32;
 
 CFX_WideString GetFullName(CPDF_Dictionary* pFieldDict) {
   CFX_WideString full_name;
   CPDF_Dictionary* pLevel = pFieldDict;
   while (pLevel) {
     CFX_WideString short_name = pLevel->GetUnicodeTextBy("T");
@@ skipping 676 matching lines @@
   CPDF_Object* pAttr = pFieldDict->GetElementValue(name);
   if (pAttr) {
     return pAttr;
   }
   CPDF_Dictionary* pParent = pFieldDict->GetDictBy("Parent");
   if (!pParent) {
     return NULL;
   }
   return FPDF_GetFieldAttr(pParent, name, nLevel + 1);
 }