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

fpdfsdk/src/fpdfdoc_unittest.cpp

 // Copyright 2016 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.
 
 #include "public/fpdf_doc.h"
 
 #include <memory>
 #include <vector>
 
+#include "core/include/fpdfapi/cpdf_document.h"
 #include "core/include/fpdfapi/fpdf_module.h"
 #include "core/include/fpdfdoc/fpdf_doc.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/test_support.h"
 
 #ifdef PDF_ENABLE_XFA
 #include "fpdfsdk/include/fpdfxfa/fpdfxfa_app.h"
 #include "fpdfsdk/include/fpdfxfa/fpdfxfa_doc.h"
 #endif  // PDF_ENABLE_XFA
 
@@ skipping 192 matching lines @@
     // Title with no match.
     std::unique_ptr<unsigned short, pdfium::FreeDeleter> title =
         GetFPDFWideString(L"Chapter 8");
     EXPECT_EQ(nullptr, FPDFBookmark_Find(m_pDoc.get(), title.get()));
 
     // Title with a match.
     title = GetFPDFWideString(L"Chapter 3");
     EXPECT_EQ(bookmarks[3].obj, FPDFBookmark_Find(m_pDoc.get(), title.get()));
   }
 }