[mus+ash] Removes WmWindow from screen_dimmer and video_detector

ash/shell.cc

Index: ash/shell.cc
diff --git a/ash/shell.cc b/ash/shell.cc
index 1ddf282c66db499bd490bedf2394572def36d3f4..72e09689ce4e44c613160fbd8239c3d666480583 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -347,7 +347,7 @@ void Shell::OnCastingSessionStartedOrStopped(bool started) {
     observer.OnCastingSessionStartedOrStopped(started);
 }
 
-void Shell::OnRootWindowAdded(WmWindow* root_window) {
+void Shell::OnRootWindowAdded(aura::Window* root_window) {
   for (auto& observer : shell_observers_)
     observer.OnRootWindowAdded(root_window);
 }
@@ -513,7 +513,7 @@ void Shell::NotifyOverviewModeEnded() {
 }
 
 void Shell::NotifyFullscreenStateChanged(bool is_fullscreen,
-                                         WmWindow* root_window) {
+                                         aura::Window* root_window) {
   for (auto& observer : shell_observers_)
     observer.OnFullscreenStateChanged(is_fullscreen, root_window);
 }