Deletion/ownership

mojo/services/public/cpp/view_manager/view_tree_node_observer.h

Index: mojo/services/public/cpp/view_manager/view_tree_node_observer.h
diff --git a/mojo/services/public/cpp/view_manager/view_tree_node_observer.h b/mojo/services/public/cpp/view_manager/view_tree_node_observer.h
index 4b4e6e0c17b1484307e26ec2c6f90903098bb017..ac55ae6755affe5e766c1e0104383e4f0cb9efae 100644
--- a/mojo/services/public/cpp/view_manager/view_tree_node_observer.h
+++ b/mojo/services/public/cpp/view_manager/view_tree_node_observer.h
@@ -33,6 +33,9 @@ class ViewTreeNodeObserver {
 
   virtual void OnTreeChange(const TreeChangeParams& params) {}
 
+  virtual void OnNodeDestroy(ViewTreeNode* node,
+                             DispositionChangePhase phase) {}
+
  protected:
   virtual ~ViewTreeNodeObserver() {}
 };