[mus+ash] Removes WmWindow from ash/wm/root_window_finder.h

ash/mus/screen_mus.cc

Index: ash/mus/screen_mus.cc
diff --git a/ash/mus/screen_mus.cc b/ash/mus/screen_mus.cc
index 492579c27cecbf0b1b5cd9db50773adf1cbffa7b..3d91c123c50e19c58d4d98426d65fba160cf5d56 100644
--- a/ash/mus/screen_mus.cc
+++ b/ash/mus/screen_mus.cc
@@ -5,7 +5,6 @@
 #include "ash/mus/screen_mus.h"
 
 #include "ash/wm/root_window_finder.h"
-#include "ash/wm_window.h"
 #include "services/ui/public/interfaces/display/display_controller.mojom.h"
 #include "ui/aura/client/screen_position_client.h"
 #include "ui/aura/env.h"
@@ -57,8 +56,7 @@ bool ScreenMus::IsWindowUnderCursor(gfx::NativeWindow window) {
 }
 
 gfx::NativeWindow ScreenMus::GetWindowAtScreenPoint(const gfx::Point& point) {
-  aura::Window* root_window =
-      WmWindow::GetAuraWindow(wm::GetRootWindowAt(point));
+  aura::Window* root_window = wm::GetRootWindowAt(point);
   aura::client::ScreenPositionClient* position_client =
       aura::client::GetScreenPositionClient(root_window);