aura: Start converting event-filters into event-handlers.

ui/base/events/event_target.h

Index: ui/base/events/event_target.h
diff --git a/ui/base/events/event_target.h b/ui/base/events/event_target.h
index 99eeb93acfa4faaff8e80f5d913eacbc21eeae16..5687c6b5729ea8fbfb203668d7ead309d4472988 100644
--- a/ui/base/events/event_target.h
+++ b/ui/base/events/event_target.h
@@ -32,6 +32,21 @@ class UI_EXPORT EventTarget : public EventHandler {
     DISALLOW_COPY_AND_ASSIGN(TestApi);
   };
 
+  class DispatcherApi {
+   public:
+    explicit DispatcherApi(EventTarget* target) : target_(target) {}
+
+    const EventHandlerList& pre_target_list() const {
+      return target_->pre_target_list_;
+    }
+
+   private:
+    DispatcherApi();
+    EventTarget* target_;
+
+    DISALLOW_COPY_AND_ASSIGN(DispatcherApi);
+  };
+
   EventTarget();
   virtual ~EventTarget();