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

core/src/fpdfdoc/doc_ocg.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/include/fpdfapi/cpdf_document.h"
 #include "core/include/fpdfdoc/fpdf_doc.h"
 
 static int32_t FPDFDOC_OCG_FindGroup(const CPDF_Object* pObject,
                                      const CPDF_Dictionary* pGroupDict) {
   if (!pObject || !pGroupDict)
     return -1;
 
   if (const CPDF_Array* pArray = pObject->AsArray()) {
     FX_DWORD dwCount = pArray->GetCount();
     for (FX_DWORD i = 0; i < dwCount; i++) {
@@ skipping 256 matching lines @@
   }
   CFX_ByteString csType = pOCGDict->GetStringBy("Type", "OCG");
   if (csType == "OCG") {
     return GetOCGVisible(pOCGDict);
   }
   return LoadOCMDState(pOCGDict, FALSE);
 }
 void CPDF_OCContext::ResetOCContext() {
   m_OCGStates.clear();
 }