[mus+ash] Removes WmWindow from screen_dimmer and video_detector

ash/wm/video_detector.cc

Index: ash/wm/video_detector.cc
diff --git a/ash/wm/video_detector.cc b/ash/wm/video_detector.cc
index 22f9efb34259db87efbc057615856368e5a22e41..9d28f6473339e2e1759257845aaf29b76ba1a5df 100644
--- a/ash/wm/video_detector.cc
+++ b/ash/wm/video_detector.cc
@@ -147,16 +147,15 @@ void VideoDetector::OnChromeTerminating() {
 }
 
 void VideoDetector::OnFullscreenStateChanged(bool is_fullscreen,
-                                             WmWindow* root_window) {
-  aura::Window* aura_window = root_window->aura_window();
-  if (is_fullscreen && !fullscreen_root_windows_.count(aura_window)) {
-    fullscreen_root_windows_.insert(aura_window);
-    if (!window_observer_manager_.IsObserving(aura_window))
-      window_observer_manager_.Add(aura_window);
+                                             aura::Window* root_window) {
+  if (is_fullscreen && !fullscreen_root_windows_.count(root_window)) {
+    fullscreen_root_windows_.insert(root_window);
+    if (!window_observer_manager_.IsObserving(root_window))
+      window_observer_manager_.Add(root_window);
     UpdateState();
-  } else if (!is_fullscreen && fullscreen_root_windows_.count(aura_window)) {
-    fullscreen_root_windows_.erase(aura_window);
-    window_observer_manager_.Remove(aura_window);
+  } else if (!is_fullscreen && fullscreen_root_windows_.count(root_window)) {
+    fullscreen_root_windows_.erase(root_window);
+    window_observer_manager_.Remove(root_window);
     UpdateState();
   }
 }