Move shelf/launcher/status_area_widget/panel_layout_manager to RootWindowController

ash/display/display_controller.cc

Index: ash/display/display_controller.cc
diff --git a/ash/display/display_controller.cc b/ash/display/display_controller.cc
index b12b4f22bbc3e044f4ac4ac51114cac8492b9d03..660841f8de396c80d8846a29a64fc980aab6f6ba 100644
--- a/ash/display/display_controller.cc
+++ b/ash/display/display_controller.cc
@@ -469,7 +469,7 @@ void DisplayController::OnDisplayRemoved(const gfx::Display& display) {
   DCHECK(controller);
   controller->MoveWindowsTo(GetPrimaryRootWindow());
   // Delete most of root window related objects, but don't delete
-  // root window itself yet because the stak may be using it.
+  // root window itself yet because the stack may be using it.
   controller->Shutdown();
   MessageLoop::current()->DeleteSoon(FROM_HERE, controller);
 }