[mus+ash] Removes WmWindow from screen_dimmer and video_detector

ash/wm/screen_dimmer.h

 // Copyright (c) 2012 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_SCREEN_DIMMER_H_
 #define ASH_WM_SCREEN_DIMMER_H_
 
 #include <memory>
 #include <vector>
 
 #include "ash/ash_export.h"
 #include "ash/shell_observer.h"
 #include "base/macros.h"
 
-namespace aura {
-class Window;
-}
-
 namespace ash {
 
 class WindowDimmer;
 
 template <typename UserData>
 class WindowUserData;
 
 namespace test {
 class ScreenDimmerTest;
 }
@@ skipping 27 matching lines @@
   static ScreenDimmer* FindForTest(int container_id);
 
  private:
   friend class test::ScreenDimmerTest;
 
   // Returns the aura::Windows (one per display) that correspond to
   // |container_|.
   std::vector<aura::Window*> GetAllContainers();
 
   // ShellObserver:
-  void OnRootWindowAdded(WmWindow* root_window) override;
+  void OnRootWindowAdded(aura::Window* root_window) override;
 
   // Update the dimming state. This will also create a new DimWindow
   // if necessary. (Used when a new display is connected)
   void Update(bool should_dim);
 
   const Container container_;
 
   // Are we currently dimming the screen?
   bool is_dimming_;
   bool at_bottom_;
 
   // Owns the WindowDimmers.
   std::unique_ptr<WindowUserData<WindowDimmer>> window_dimmers_;
 
   DISALLOW_COPY_AND_ASSIGN(ScreenDimmer);
 };
 
 }  // namespace ash
 
 #endif  // ASH_WM_SCREEN_DIMMER_H_