[mus+ash] Removes WmWindow from screen_dimmer and video_detector

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index 7a644b054a22f8add5e5d0b10fab9b903c3955c9..51f5df159047662cf70a5b79ca5d1e7bf4df58ae 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -285,7 +285,7 @@ class ASH_EXPORT Shell : public SessionObserver,
   void OnCastingSessionStartedOrStopped(bool started);
 
   // Called when a root window is created.
-  void OnRootWindowAdded(WmWindow* root_window);
+  void OnRootWindowAdded(aura::Window* root_window);
 
   // Creates a virtual keyboard. Deletes the old virtual keyboard if it already
   // exists.
@@ -586,7 +586,8 @@ class ASH_EXPORT Shell : public SessionObserver,
   void NotifyOverviewModeEnded();
 
   // Notifies observers that fullscreen mode has changed for |root_window|.
-  void NotifyFullscreenStateChanged(bool is_fullscreen, WmWindow* root_window);
+  void NotifyFullscreenStateChanged(bool is_fullscreen,
+                                    aura::Window* root_window);
 
   // Notifies observers that |pinned_window| changed its pinned window state.
   void NotifyPinnedStateChanged(aura::Window* pinned_window);