Generalize layer mirroring for phantom windows

ui/compositor/layer_owner.cc

Index: ui/compositor/layer_owner.cc
diff --git a/ui/compositor/layer_owner.cc b/ui/compositor/layer_owner.cc
index d94ff2cc8239813e500d1296b780ae5cd16cff9d..9989f5db50511a342bd8870b520f3936ade61f6a 100644
--- a/ui/compositor/layer_owner.cc
+++ b/ui/compositor/layer_owner.cc
@@ -38,24 +38,8 @@ std::unique_ptr<Layer> LayerOwner::RecreateLayer() {
   LayerDelegate* old_delegate = old_layer->delegate();
   old_layer->set_delegate(NULL);
 
-  const gfx::Rect layer_bounds(old_layer->bounds());
-  Layer* new_layer = new ui::Layer(old_layer->type());
+  Layer* new_layer = old_layer->Clone().release();
   SetLayer(new_layer);
-  new_layer->SetVisible(old_layer->GetTargetVisibility());
-  new_layer->SetOpacity(old_layer->GetTargetOpacity());
-  new_layer->SetBounds(layer_bounds);
-  new_layer->SetMasksToBounds(old_layer->GetMasksToBounds());
-  new_layer->set_name(old_layer->name());
-  new_layer->SetFillsBoundsOpaquely(old_layer->fills_bounds_opaquely());
-  new_layer->SetFillsBoundsCompletely(old_layer->FillsBoundsCompletely());
-  new_layer->SetSubpixelPositionOffset(old_layer->subpixel_position_offset());
-  new_layer->SetLayerInverted(old_layer->layer_inverted());
-  new_layer->SetTransform(old_layer->GetTargetTransform());
-  if (old_layer->type() == LAYER_SOLID_COLOR)
-    new_layer->SetColor(old_layer->GetTargetColor());
-  SkRegion* alpha_shape = old_layer->alpha_shape();
-  if (alpha_shape)
-    new_layer->SetAlphaShape(base::MakeUnique<SkRegion>(*alpha_shape));
 
   if (old_layer->parent()) {
     // Install new layer as a sibling of the old layer, stacked below it.