Converts ash to use aura-mus

ash/aura/wm_window_aura.h

Index: ash/aura/wm_window_aura.h
diff --git a/ash/aura/wm_window_aura.h b/ash/aura/wm_window_aura.h
index 9bc3699dd5cb56355d5d9555c1b075649d935702..e45f12a5f932fd45cd458f616e5600324cf45043 100644
--- a/ash/aura/wm_window_aura.h
+++ b/ash/aura/wm_window_aura.h
@@ -188,7 +188,12 @@ class ASH_EXPORT WmWindowAura : public WmWindow,
   void AddLimitedPreTargetHandler(ui::EventHandler* handler) override;
   void RemoveLimitedPreTargetHandler(ui::EventHandler* handler) override;
 
- private:
+ protected:
+  // Returns true if a WmWindowAura has been created for |window|.
+  static bool HasInstance(const aura::Window* window);
+
+  base::ObserverList<WmWindowObserver>& observers() { return observers_; }
+
   // aura::WindowObserver:
   void OnWindowHierarchyChanging(const HierarchyChangeParams& params) override;
   void OnWindowHierarchyChanged(const HierarchyChangeParams& params) override;
@@ -211,6 +216,7 @@ class ASH_EXPORT WmWindowAura : public WmWindow,
   void OnTransientChildRemoved(aura::Window* window,
                                aura::Window* transient) override;
 
+ private:
   aura::Window* window_;
 
   base::ObserverList<WmWindowObserver> observers_;