Introduce CPDF_Document::FromFPDFDocument().

core/include/fpdfapi/fpdf_parser.h

Index: core/include/fpdfapi/fpdf_parser.h
diff --git a/core/include/fpdfapi/fpdf_parser.h b/core/include/fpdfapi/fpdf_parser.h
index 04c7d90f6fc067cae49787f340f27f41ecd0840b..b58cf14974c2ea21ec2ef6a4047da2ab3b54aebe 100644
--- a/core/include/fpdfapi/fpdf_parser.h
+++ b/core/include/fpdfapi/fpdf_parser.h
@@ -7,6 +7,7 @@
 #ifndef CORE_INCLUDE_FPDFAPI_FPDF_PARSER_H_
 #define CORE_INCLUDE_FPDFAPI_FPDF_PARSER_H_
 
+#include "../../../public/fpdfview.h"
 #include "../fxcrt/fx_system.h"
 #include "fpdf_objects.h"
 
@@ -56,6 +57,8 @@ extern const FX_WORD PDFDocEncoding[256];
 
 class CPDF_Document : public CFX_PrivateData, public CPDF_IndirectObjects {
  public:
+  static CPDF_Document* FromFPDFDocument(FPDF_DOCUMENT document);
+
   CPDF_Document();
   explicit CPDF_Document(CPDF_Parser* pParser);