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

fpdfsdk/src/fpdfdoc.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 "public/fpdf_doc.h"
 
 #include <set>
 
+#include "core/include/fpdfapi/cpdf_document.h"
 #include "fpdfsdk/include/fsdk_define.h"
 #include "third_party/base/stl_util.h"
 
 namespace {
 
 int THISMODULE = 0;
 
 CPDF_Bookmark FindBookmark(const CPDF_BookmarkTree& tree,
                            CPDF_Bookmark bookmark,
                            const CFX_WideString& title,
@@ skipping 337 matching lines @@
     return 0;
   CFX_WideString text = pInfo->GetUnicodeTextBy(tag);
   // Use UTF-16LE encoding
   CFX_ByteString encodedText = text.UTF16LE_Encode();
   unsigned long len = encodedText.GetLength();
   if (buffer && buflen >= len) {
     FXSYS_memcpy(buffer, encodedText.c_str(), len);
   }
   return len;
 }