Makes WindowTree::DeleteWindow() unembed for roots

services/ui/ws/server_window.h

Index: services/ui/ws/server_window.h
diff --git a/services/ui/ws/server_window.h b/services/ui/ws/server_window.h
index 69e31bd4d59e48b4a42a1e4e7345102d33a8ba7d..4e0d9fce34ef6f76600c6c10321a263755689d1d 100644
--- a/services/ui/ws/server_window.h
+++ b/services/ui/ws/server_window.h
@@ -185,6 +185,9 @@ class ServerWindow {
 
   ServerWindowDelegate* delegate() { return delegate_; }
 
+  // Called when the window is no longer an embed root.
+  void OnEmbeddedAppDisconnected();
+
 #if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
   std::string GetDebugWindowHierarchy() const;
   std::string GetDebugWindowInfo() const;