Generalize layer mirroring for phantom windows

ash/aura/wm_window_aura.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/aura/wm_window_aura.h"
 
 #include "ash/aura/aura_layout_manager_adapter.h"
 #include "ash/aura/wm_root_window_controller_aura.h"
 #include "ash/aura/wm_shell_aura.h"
 #include "ash/common/ash_constants.h"
@@ skipping 480 matching lines @@
 
 void WmWindowAura::SetBoundsDirectCrossFade(const gfx::Rect& bounds) {
   const gfx::Rect old_bounds = window_->bounds();
 
   // Create fresh layers for the window and all its children to paint into.
   // Takes ownership of the old layer and all its children, which will be
   // cleaned up after the animation completes.
   // Specify |set_bounds| to true here to keep the old bounds in the child
   // windows of |window|.
   std::unique_ptr<ui::LayerTreeOwner> old_layer_owner =
-      ::wm::RecreateLayers(window_, nullptr);
+      ::wm::RecreateLayers(window_);
   ui::Layer* old_layer = old_layer_owner->root();
   DCHECK(old_layer);
   ui::Layer* new_layer = window_->layer();
 
   // Resize the window to the new size, which will force a layout and paint.
   SetBoundsDirect(bounds);
 
   // Ensure the higher-resolution layer is on top.
   bool old_on_top = (old_bounds.width() > bounds.width());
   if (old_on_top)
@@ skipping 386 matching lines @@
                     OnTransientChildAdded(this, Get(transient)));
 }
 
 void WmWindowAura::OnTransientChildRemoved(aura::Window* window,
                                            aura::Window* transient) {
   FOR_EACH_OBSERVER(WmTransientWindowObserver, transient_observers_,
                     OnTransientChildRemoved(this, Get(transient)));
 }
 
 }  // namespace ash