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

core/src/fpdfapi/fpdf_page/fpdf_page_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 "core/src/fpdfapi/fpdf_page/pageint.h"
 
 #include "core/include/fdrm/fx_crypt.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_font/font_int.h"
 
 class CPDF_PageModule : public IPDF_PageModule {
  public:
   CPDF_PageModule()
       : m_StockGrayCS(nullptr, PDFCS_DEVICEGRAY),
         m_StockRGBCS(nullptr, PDFCS_DEVICERGB),
         m_StockCMYKCS(nullptr, PDFCS_DEVICECMYK),
@@ skipping 578 matching lines @@
 }
 
 CPDF_CountedPattern* CPDF_DocPageData::FindPatternPtr(
     CPDF_Object* pPatternObj) const {
   if (!pPatternObj)
     return nullptr;
 
   auto it = m_PatternMap.find(pPatternObj);
   return it != m_PatternMap.end() ? it->second : nullptr;
 }