Makes display roots be destroyed by client

services/ui/demo/mus_demo.cc

Index: services/ui/demo/mus_demo.cc
diff --git a/services/ui/demo/mus_demo.cc b/services/ui/demo/mus_demo.cc
index 45ebcc1b5dc5d6ec6835ec281a920e046358b6c6..136ad7a81f4e9b14ba01b552ac51932217cb4093 100644
--- a/services/ui/demo/mus_demo.cc
+++ b/services/ui/demo/mus_demo.cc
@@ -130,6 +130,10 @@ void MusDemo::OnWmNewDisplay(Window* window, const display::Display& display) {
                base::Bind(&MusDemo::DrawFrame, base::Unretained(this)));
 }
 
+void MusDemo::OnWmDisplayRemoved(ui::Window* window) {
+  window->Destroy();
+}
+
 void MusDemo::OnWmPerformMoveLoop(Window* window,
                                   mojom::MoveLoopSource source,
                                   const gfx::Point& cursor_location,