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

core/src/fpdfapi/fpdf_page/fpdf_page.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 "core/src/fpdfapi/fpdf_page/pageint.h"
 
 #include <algorithm>
 
+#include "core/include/fpdfapi/cpdf_document.h"
 #include "core/include/fpdfapi/fpdf_module.h"
 #include "core/include/fpdfapi/fpdf_page.h"
 #include "third_party/base/stl_util.h"
 
 CPDF_PageObject::CPDF_PageObject() {}
 
 CPDF_PageObject::~CPDF_PageObject() {}
 
 void CPDF_PageObject::CopyData(const CPDF_PageObject* pSrc) {
   CopyStates(*pSrc);
@@ skipping 731 matching lines @@
   matrix = m_PageMatrix;
   matrix.Concat(display_matrix);
 }
 
 CPDF_ParseOptions::CPDF_ParseOptions() {
   m_bTextOnly = FALSE;
   m_bMarkedContent = TRUE;
   m_bSeparateForm = TRUE;
   m_bDecodeInlineImage = FALSE;
 }