Cleans up usage of ViewManagerServiceImpl::roots_

mojo/services/public/cpp/view_manager/lib/node.cc

Index: mojo/services/public/cpp/view_manager/lib/node.cc
diff --git a/mojo/services/public/cpp/view_manager/lib/node.cc b/mojo/services/public/cpp/view_manager/lib/node.cc
index 292cf29e381ca53f29914b2495ccabbdf1598d71..738a5be97c4750e9f6db3e5e53282d1cc65e7297 100644
--- a/mojo/services/public/cpp/view_manager/lib/node.cc
+++ b/mojo/services/public/cpp/view_manager/lib/node.cc
@@ -216,8 +216,17 @@ void Node::Destroy() {
 
   if (manager_)
     static_cast<ViewManagerClientImpl*>(manager_)->DestroyNode(id_);
-  while (!children_.empty())
-    children_.front()->Destroy();
+  while (!children_.empty()) {
+    Node* child = children_.front();
+    if (!OwnsNode(manager_, child)) {
+      NodePrivate(child).ClearParent();
+      children_.erase(children_.begin());
+    } else {
+      child->Destroy();
+      DCHECK(std::find(children_.begin(), children_.end(), child) ==
+             children_.end());
+    }
+  }
   LocalDestroy();
 }