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

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/cpdf_document.h"
 #include "core/include/fpdfapi/fpdf_module.h"
 #include "core/include/fpdfapi/fpdf_page.h"
 #include "core/src/fpdfapi/fpdf_page/pageint.h"
 
 CPDF_Document::CPDF_Document() : CPDF_IndirectObjectHolder(NULL) {
   m_pRootDict = NULL;
   m_pInfoDict = NULL;
   m_bLinearized = FALSE;
   m_dwFirstPageNo = 0;
   m_dwFirstPageObjNum = 0;
@@ skipping 1122 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());
   }
 }