Only dispatch menu events if they have a valid target.

ui/views/controls/menu/menu_controller.h

Index: ui/views/controls/menu/menu_controller.h
diff --git a/ui/views/controls/menu/menu_controller.h b/ui/views/controls/menu/menu_controller.h
index 910d3809f8276930c4e630f7cf2cfa84dedeabd1..56a0d92306757125962e3da27e9846be295db0ab 100644
--- a/ui/views/controls/menu/menu_controller.h
+++ b/ui/views/controls/menu/menu_controller.h
@@ -91,6 +91,10 @@ class VIEWS_EXPORT MenuController : public WidgetObserver {
   // Whether or not drag operation is in progress.
   bool drag_in_progress() const { return drag_in_progress_; }
 
+  // Returns the owner of child windows.
+  // WARNING: this may be NULL.
+  Widget* owner() { return owner_; }
+
   // Get the anchor position wich is used to show this menu.
   MenuAnchorPosition GetAnchorPosition() { return state_.anchor; }