[mus+ash] Removes WmWindow from ash/wm/overview and ash/wm/workspace

ash/wm/workspace/backdrop_controller.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 "ash/wm/workspace/backdrop_controller.h"
 
 #include "ash/accessibility_delegate.h"
 #include "ash/public/cpp/shell_window_ids.h"
 #include "ash/root_window_controller.h"
 #include "ash/shared/app_types.h"
 #include "ash/shell.h"
 #include "ash/system/tray/system_tray_notifier.h"
 #include "ash/wm/window_util.h"
 #include "ash/wm/workspace/backdrop_delegate.h"
-#include "ash/wm_window.h"
 #include "base/auto_reset.h"
 #include "chromeos/audio/chromeos_sounds.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/compositor/layer.h"
 #include "ui/compositor/scoped_layer_animation_settings.h"
 #include "ui/views/widget/widget.h"
 #include "ui/wm/core/window_animations.h"
 #include "ui/wm/core/window_util.h"
 
 namespace ash {
@@ skipping 209 matching lines @@
   if (!backdrop_)
     return;
   backdrop_->Close();
   backdrop_ = nullptr;
   backdrop_window_ = nullptr;
   original_event_handler_ = nullptr;
   backdrop_event_handler_.reset();
 }
 
 }  // namespace ash