Generalize layer mirroring for phantom windows

chrome/browser/ui/ash/multi_user/user_switch_animator_chromeos.cc

 // Copyright 2014 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 "chrome/browser/ui/ash/multi_user/user_switch_animator_chromeos.h"
 
 #include "ash/aura/wm_window_aura.h"
 #include "ash/common/shelf/shelf_layout_manager.h"
 #include "ash/common/shelf/shelf_widget.h"
 #include "ash/common/shelf/wm_shelf.h"
@@ skipping 316 matching lines @@
             // Maximized windows should be hidden, but visually kept visible
             // in order to prevent showing the background while the animation is
             // in progress. Therefore we detach the old layer and recreate fresh
             // ones. The old layers will be destructed at the animation step
             // |ANIMATION_STEP_FINALIZE|.
             // old_layers_.push_back(wm::RecreateLayers(window));
             // We only want to do this for the first (foreground) maximized
             // window we encounter.
             found_foreground_maximized_window = true;
             ui::LayerTreeOwner* old_layer =
-                wm::RecreateLayers(window, nullptr).release();
+                wm::RecreateLayers(window).release();
             window->layer()->parent()->StackAtBottom(old_layer->root());
             new MaximizedWindowAnimationWatcher(window->layer()->GetAnimator(),
                                                 old_layer);
           }
 
           owner_->SetWindowVisibility(window, false, duration);
         }
       }
 
       // Show new user.
@@ skipping 89 matching lines @@
         if (itr != window_to_entry_map.end()) {
           windows_by_account_id_[itr->second->show_for_user()].push_back(
               child_window);
         }
       }
     }
   }
 }
 
 }  // namespace chrome