Promotes WmWindowMus functions to WmWindowAura and nukes WmWindowMus

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 3542255eb8808f77904522e03344e6f26ba17ecd..9c1b05d47e50d7b8c23fcf72c5bac51d2e43bdec 100644
--- a/ash/aura/wm_window_aura.h
+++ b/ash/aura/wm_window_aura.h
@@ -28,10 +28,11 @@ class ASH_EXPORT WmWindowAura : public WmWindow,
 
   // Returns a WmWindow for an aura::Window, creating if necessary. |window| may
   // be null, in which case null is returned.
-  static WmWindow* Get(aura::Window* window) {
-    return const_cast<WmWindow*>(Get(const_cast<const aura::Window*>(window)));
+  static WmWindowAura* Get(aura::Window* window) {
+    return const_cast<WmWindowAura*>(
+        Get(const_cast<const aura::Window*>(window)));
   }
-  static const WmWindow* Get(const aura::Window* window);
+  static const WmWindowAura* Get(const aura::Window* window);
 
   static std::vector<WmWindow*> FromAuraWindows(
       const std::vector<aura::Window*>& aura_windows);
@@ -50,6 +51,8 @@ class ASH_EXPORT WmWindowAura : public WmWindow,
   // See description of |children_use_extended_hit_region_|.
   bool ShouldUseExtendedHitRegion() const;
 
+  wm::WindowState* GetWindowState() { return WmWindow::GetWindowState(); }
+
   // WmWindow:
   void Destroy() override;
   const WmWindow* GetRootWindow() const override;