Avoid two targeting phases in aura client-lib and EventProcessor.

ash/root_window_controller.cc

Index: ash/root_window_controller.cc
diff --git a/ash/root_window_controller.cc b/ash/root_window_controller.cc
index be538ba54484eb94cc4a183971ce60ef03bfda59..2847b11855c97965a305debafd1bd42196a4f101 100644
--- a/ash/root_window_controller.cc
+++ b/ash/root_window_controller.cc
@@ -480,8 +480,9 @@ WmWindow* RootWindowController::FindEventTarget(
                             location_in_root, ui::EventTimeForNow(),
                             ui::EF_NONE, ui::EF_NONE);
   ui::EventTarget* event_handler =
-      static_cast<ui::EventTarget*>(root_window)
-          ->GetEventTargeter()
+      root_window->GetHost()
+          ->dispatcher()
+          ->GetDefaultEventTargeter()
           ->FindTargetForEvent(root_window, &test_event);
   return WmWindow::Get(static_cast<aura::Window*>(event_handler));
 }