chromeos: removes WmWindow usage from MultiWindowResizeController

ash/wm/workspace/workspace_event_handler.cc

Index: ash/wm/workspace/workspace_event_handler.cc
diff --git a/ash/wm/workspace/workspace_event_handler.cc b/ash/wm/workspace/workspace_event_handler.cc
index 39d8ec0da75ac04cbde578905af0ea645b8bd2b6..433ee9a0bcb98ef1ccb2ee57caae7b272ef90452 100644
--- a/ash/wm/workspace/workspace_event_handler.cc
+++ b/ash/wm/workspace/workspace_event_handler.cc
@@ -31,7 +31,7 @@ void WorkspaceEventHandler::OnMouseEvent(ui::MouseEvent* event,
   switch (event->type()) {
     case ui::ET_MOUSE_MOVED: {
       int component = target->GetNonClientComponent(event->location());
-      multi_window_resize_controller_.Show(target, component,
+      multi_window_resize_controller_.Show(target->aura_window(), component,
                                            event->location());
       break;
     }