Converts MruWindowTracker to work with common types

ash/mus/bridge/wm_window_mus.h

 // 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.
 
 #ifndef ASH_MUS_BRIDGE_WM_WINDOW_MUS_H_
 #define ASH_MUS_BRIDGE_WM_WINDOW_MUS_H_
 
 #include <memory>
 
 #include "ash/common/shell_window_ids.h"
@@ skipping 189 matching lines @@
       BoundsInScreenBehavior behavior) override;
   void SetSnapsChildrenToPhysicalPixelBoundary() override;
   void SnapToPixelBoundaryIfNecessary() override;
   void SetChildrenUseExtendedHitRegion() override;
   void SetDescendantsStayInSameRootWindow(bool value) override;
   void AddObserver(WmWindowObserver* observer) override;
   void RemoveObserver(WmWindowObserver* observer) override;
 
  private:
   // mus::WindowObserver:
+  void OnTreeChanging(const TreeChangeParams& params) override;
   void OnTreeChanged(const TreeChangeParams& params) override;
   void OnWindowReordered(::mus::Window* window,
                          ::mus::Window* relative_window,
                          ::mus::mojom::OrderDirection direction) override;
   void OnWindowSharedPropertyChanged(
       ::mus::Window* window,
       const std::string& name,
       const std::vector<uint8_t>* old_data,
       const std::vector<uint8_t>* new_data) override;
   void OnWindowBoundsChanged(::mus::Window* window,
                              const gfx::Rect& old_bounds,
                              const gfx::Rect& new_bounds) override;
   void OnWindowDestroying(::mus::Window* window) override;
+  void OnWindowDestroyed(::mus::Window* window) override;
 
   ::mus::Window* window_;
 
   // The shell window id of this window. Shell window ids are defined in
   // ash/common/shell_window_ids.h.
   int shell_window_id_ = kShellWindowId_Invalid;
 
   std::unique_ptr<wm::WindowState> window_state_;
 
   views::Widget* widget_ = nullptr;
@@ skipping 14 matching lines @@
   // resizing easier.
   bool children_use_extended_hit_region_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(WmWindowMus);
 };
 
 }  // namespace mus
 }  // namespace ash
 
 #endif  // ASH_MUS_BRIDGE_WM_WINDOW_MUS_H_