Makes WindowTree::DeleteWindow() unembed for roots

services/ui/ws/server_window.cc

Index: services/ui/ws/server_window.cc
diff --git a/services/ui/ws/server_window.cc b/services/ui/ws/server_window.cc
index b36e944fde4915378538afb75c22d9f0065e2bf7..5a6ca3c004b0c13ffdd26a697312e39345b8acab 100644
--- a/services/ui/ws/server_window.cc
+++ b/services/ui/ws/server_window.cc
@@ -385,6 +385,11 @@ void ServerWindow::SetUnderlayOffset(const gfx::Vector2d& offset) {
   delegate_->OnScheduleWindowPaint(this);
 }
 
+void ServerWindow::OnEmbeddedAppDisconnected() {
+  FOR_EACH_OBSERVER(ServerWindowObserver, observers_,
+                    OnWindowEmbeddedAppDisconnected(this));
+}
+
 #if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
 std::string ServerWindow::GetDebugWindowHierarchy() const {
   std::string result;