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

ash/wm/mru_window_tracker.h

 // Copyright 2013 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.
 
 #ifndef ASH_WM_MRU_WINDOW_TRACKER_H_
 #define ASH_WM_MRU_WINDOW_TRACKER_H_
 
 #include <list>
 #include <vector>
 
 #include "ash/ash_export.h"
 #include "base/macros.h"
 #include "ui/aura/window_observer.h"
 #include "ui/wm/public/activation_change_observer.h"
 
 namespace ash {
 
-class WmWindow;
-
 // Maintains a most recently used list of windows. This is used for window
 // cycling using Alt+Tab and overview mode.
 class ASH_EXPORT MruWindowTracker
     : public aura::client::ActivationChangeObserver,
       public aura::WindowObserver {
  public:
-  using WindowList = std::vector<WmWindow*>;
+  using WindowList = std::vector<aura::Window*>;
 
   MruWindowTracker();
   ~MruWindowTracker() override;
 
   // Returns the set of windows which can be cycled through using the tracked
   // list of most recently used windows.
   WindowList BuildMruWindowList() const;
 
   // This does the same thing as the above, but ignores the system modal dialog
   // state and hence the returned list could contain more windows if a system
   // modal dialog window is present.
   WindowList BuildWindowListIgnoreModal() const;
 
   // Starts or stops ignoring window activations. If no longer ignoring
   // activations the currently active window is moved to the front of the
   // MRU window list. Used by WindowCycleList to avoid adding all cycled
   // windows to the front of the MRU window list.
   void SetIgnoreActivations(bool ignore);
 
  private:
   // Updates the mru_windows_ list to insert/move |active_window| at/to the
   // front.
-  void SetActiveWindow(WmWindow* active_window);
+  void SetActiveWindow(aura::Window* active_window);
 
   // Overridden from aura::client::ActivationChangeObserver:
   void OnWindowActivated(ActivationReason reason,
                          aura::Window* gained_active,
                          aura::Window* lost_active) override;
 
   // Overridden from aura::WindowObserver:
   void OnWindowDestroyed(aura::Window* window) override;
 
   // List of windows that have been activated in containers that we cycle
   // through, sorted by most recently used.
-  std::list<WmWindow*> mru_windows_;
+  std::list<aura::Window*> mru_windows_;
 
   bool ignore_window_activations_;
 
   DISALLOW_COPY_AND_ASSIGN(MruWindowTracker);
 };
 
 }  // namespace ash
 
 #endif  // ASH_WM_MRU_WINDOW_TRACKER_H_