[mus+ash] Removes WmWindow from screen_dimmer and video_detector

ash/wm/workspace/workspace_layout_manager_unittest.cc

Index: ash/wm/workspace/workspace_layout_manager_unittest.cc
diff --git a/ash/wm/workspace/workspace_layout_manager_unittest.cc b/ash/wm/workspace/workspace_layout_manager_unittest.cc
index 24f6dbf6181f604e847c93660495a93f0fb1c3fe..0c1ecdce238412c3b324758514ab0190fcb10d44 100644
--- a/ash/wm/workspace/workspace_layout_manager_unittest.cc
+++ b/ash/wm/workspace/workspace_layout_manager_unittest.cc
@@ -91,7 +91,7 @@ class TestShellObserver : public ShellObserver {
   ~TestShellObserver() override { Shell::Get()->RemoveShellObserver(this); }
 
   void OnFullscreenStateChanged(bool is_fullscreen,
-                                WmWindow* root_window) override {
+                                aura::Window* root_window) override {
     call_count_++;
     is_fullscreen_ = is_fullscreen;
   }