Add functions to collect bookmarks from Pdfium

pdf/pdf_engine.h

Index: pdf/pdf_engine.h
diff --git a/pdf/pdf_engine.h b/pdf/pdf_engine.h
index cb53d3ec93be54d32ac0614b2f8363dc9e46be52..768dc8e52e3deea2b83c0b47c3b612d80d66bb79 100644
--- a/pdf/pdf_engine.h
+++ b/pdf/pdf_engine.h
@@ -24,6 +24,7 @@
 #include "ppapi/cpp/rect.h"
 #include "ppapi/cpp/size.h"
 #include "ppapi/cpp/url_loader.h"
+#include "ppapi/cpp/var_array.h"
 
 namespace pp {
 class InputEvent;
@@ -247,6 +248,14 @@ class PDFEngine {
   // Returns number of copies to be printed.
   virtual int GetCopiesToPrint() = 0;
 
+  // Returns a VarArray of Bookmarks, each a VarDictionary
+  // containing the following key/values:
+  // - "title" of type Var(std::string)
+  // - "page" of type Var(int)
+  // - "children" of type VarArray(), with each entry containing a
+  //   VarDictionary of the same structure.
+  virtual pp::VarArray GetBookmarks() = 0;
+
   // Append blank pages to make a 1-page document to a |num_pages| document.
   // Always retain the first page data.
   virtual void AppendBlankPages(int num_pages) = 0;