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 960c5f2f7f3ae80c7badeccdd3ff729e3f071271..cf1fe0527a595888f7daec3bb6a0808875a17258 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_array.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::VarArray GetBookmarks();
   virtual int GetNamedDestinationPage(const std::string& destination);
   virtual int GetFirstVisiblePage();
   virtual int GetMostVisiblePage();