Converts ShellObserver from aura::Window to ash::WmWindow

ash/wm/screen_dimmer.cc

 // Copyright (c) 2012 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/wm/screen_dimmer.h"
 
 #include "ash/shell.h"
 #include "ash/wm/dim_window.h"
 #include "base/time/time.h"
 #include "ui/aura/window_event_dispatcher.h"
@@ skipping 66 matching lines @@
 }
 
 // static
 aura::Window* ScreenDimmer::FindContainer(int container_id) {
   aura::Window* primary = Shell::GetPrimaryRootWindow();
   return container_id == kRootWindowMagicId
              ? primary
              : primary->GetChildById(container_id);
 }
 
-void ScreenDimmer::OnRootWindowAdded(aura::Window* root_window) {
+void ScreenDimmer::OnRootWindowAdded(WmWindow* root_window) {
   Update(is_dimming_);
 }
 
 void ScreenDimmer::Update(bool should_dim) {
   for (aura::Window* container : GetAllContainers(container_id_)) {
     DimWindow* dim = DimWindow::Get(container);
     if (should_dim) {
       if (!dim) {
         dim = new DimWindow(container);
         dim->SetDimOpacity(target_opacity_);
       }
       if (at_bottom_)
         dim->parent()->StackChildAtBottom(dim);
       else
         dim->parent()->StackChildAtTop(dim);
       dim->Show();
     } else {
       if (dim) {
         dim->Hide();
         delete dim;
       }
     }
   }
 }
 
 }  // namespace ash