Generalize layer mirroring for phantom windows

ash/wm/window_mirror_view.cc

Index: ash/wm/window_mirror_view.cc
diff --git a/ash/wm/window_mirror_view.cc b/ash/wm/window_mirror_view.cc
index d7f0ced6f948e0d8bae005b891180a80fca2a74b..59b7685822396e292dfdd65979a263db56a71466 100644
--- a/ash/wm/window_mirror_view.cc
+++ b/ash/wm/window_mirror_view.cc
@@ -79,7 +79,8 @@ ui::LayerDelegate* WindowMirrorView::CreateDelegate(ui::Layer* new_layer,
   if (!old_layer || !old_layer->delegate())
     return nullptr;
   delegates_.push_back(
-      base::MakeUnique<ForwardingLayerDelegate>(new_layer, old_layer));
+      base::MakeUnique<ForwardingLayerDelegate>(new_layer, old_layer,
+                                                false /* sync_bounds */));
   return delegates_.back().get();
 }