added CTRL+Click and SHIFT+Click handler for context menu, Back and Forward.

ui/base/models/menu_model.h

Index: ui/base/models/menu_model.h
diff --git a/ui/base/models/menu_model.h b/ui/base/models/menu_model.h
index a0c3627167fc5eb15f6f0716eaad9a1b5dbda206..f6feee78d5eb636fb4d081ce75f8c02122930cd7 100644
--- a/ui/base/models/menu_model.h
+++ b/ui/base/models/menu_model.h
@@ -108,9 +108,9 @@ class MenuModel {
   // Called when the item at the specified index has been activated.
   virtual void ActivatedAt(int index) = 0;
 
-  // Called when the item has been activated with a given disposition (for the
-  // case where the activation involves a navigation).
-  virtual void ActivatedAtWithDisposition(int index, int disposition);
+  // Called when the item has been activated with an event flags.
+  // |flags| is a bitsum of ui::EventFlags.
+  virtual void ActivatedAtWithFlags(int index, int flags);
 
   // Called when the menu is about to be shown.
   virtual void MenuWillShow() {}