Add functions to collect bookmarks from Pdfium

pdf/pdfium/pdfium_engine.h

Index: pdf/pdfium/pdfium_engine.h
diff --git a/pdf/pdfium/pdfium_engine.h b/pdf/pdfium/pdfium_engine.h
index 11d304a8379bcdd9ed2fa89cb9216b053ac1d4f8..d1c38bc903236290d813916ded752e77abd6d61b 100644
--- a/pdf/pdfium/pdfium_engine.h
+++ b/pdf/pdfium/pdfium_engine.h
@@ -20,6 +20,7 @@
 #include "ppapi/cpp/dev/buffer_dev.h"
 #include "ppapi/cpp/image_data.h"
 #include "ppapi/cpp/point.h"
+#include "ppapi/cpp/var_dictionary.h"
 #include "third_party/pdfium/fpdfsdk/include/fpdf_dataavail.h"
 #include "third_party/pdfium/fpdfsdk/include/fpdf_progressive.h"
 #include "third_party/pdfium/fpdfsdk/include/fpdfformfill.h"
@@ -78,6 +79,7 @@ class PDFiumEngine : public PDFEngine,
   virtual bool HasPermission(DocumentPermission permission) const;
   virtual void SelectAll();
   virtual int GetNumberOfPages();
+  virtual pp::VarDictionary GetBookmarks();
   virtual int GetNamedDestinationPage(const std::string& destination);
   virtual int GetFirstVisiblePage();
   virtual int GetMostVisiblePage();