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

core/src/fpdfapi/fpdf_page/fpdf_page_pattern.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/fpdfapi/cpdf_document.h"
 #include "core/include/fpdfapi/fpdf_page.h"
 
 namespace {
 
 const int kSingleCoordinatePair = 1;
 const int kTensorCoordinatePairs = 16;
 const int kCoonsCoordinatePairs = 12;
 
 const int kSingleColorPerPatch = 1;
 const int kQuadColorsPerPatch = 4;
@@ skipping 287 matching lines @@
       }
     }
     stream.m_BitStream.SkipBits(stream.m_nComps * stream.m_nCompBits *
                                 color_count);
     if (bGouraud)
       stream.m_BitStream.ByteAlign();
   }
   rect.Transform(pMatrix);
   return rect;
 }