Add support for mapping node tree on the client.

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

Index: mojo/services/public/cpp/view_manager/lib/view_tree_node.cc
diff --git a/mojo/services/public/cpp/view_manager/lib/view_tree_node.cc b/mojo/services/public/cpp/view_manager/lib/view_tree_node.cc
index d695ed4a45acb52a6f91fad8035a904892664a91..8ba0fd365f8688a8e01077363454d6c3b731f037 100644
--- a/mojo/services/public/cpp/view_manager/lib/view_tree_node.cc
+++ b/mojo/services/public/cpp/view_manager/lib/view_tree_node.cc
@@ -118,6 +118,8 @@ ViewTreeNode::~ViewTreeNode() {
   if (parent_)
     parent_->RemoveChild(this);
 
+  if (manager_)
+    ViewManagerPrivate(manager_).synchronizer()->DestroyViewTreeNode(id_);
 }
 
 void ViewTreeNode::AddObserver(ViewTreeNodeObserver* observer) {
@@ -129,19 +131,15 @@ void ViewTreeNode::RemoveObserver(ViewTreeNodeObserver* observer) {
 }
 
 void ViewTreeNode::AddChild(ViewTreeNode* child) {
-  ScopedTreeNotifier notifier(child, child->parent(), this);
-  if (child->parent())
-    RemoveChildImpl(child, &child->parent_->children_);
-  children_.push_back(child);
-  child->parent_ = this;
-  ViewManagerPrivate(manager_).synchronizer()->AddChild(child->id(), id_);
+  LocalAddChild(child);
+  if (manager_)
+    ViewManagerPrivate(manager_).synchronizer()->AddChild(child->id(), id_);
 }
 
 void ViewTreeNode::RemoveChild(ViewTreeNode* child) {
-  DCHECK_EQ(this, child->parent());
-  ScopedTreeNotifier(child, this, NULL);
-  RemoveChildImpl(child, &children_);
-  ViewManagerPrivate(manager_).synchronizer()->RemoveChild(child->id(), id_);
+  LocalRemoveChild(child);
+  if (manager_)
+    ViewManagerPrivate(manager_).synchronizer()->RemoveChild(child->id(), id_);
 }
 
 bool ViewTreeNode::Contains(ViewTreeNode* child) const {
@@ -152,6 +150,23 @@ bool ViewTreeNode::Contains(ViewTreeNode* child) const {
   return false;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// ViewTreeNode, private:
+
+void ViewTreeNode::LocalAddChild(ViewTreeNode* child) {
+  ScopedTreeNotifier notifier(child, child->parent(), this);
+  if (child->parent())
+    RemoveChildImpl(child, &child->parent_->children_);
+  children_.push_back(child);
+  child->parent_ = this;
+}
+
+void ViewTreeNode::LocalRemoveChild(ViewTreeNode* child) {
+  DCHECK_EQ(this, child->parent());
+  ScopedTreeNotifier(child, this, NULL);
+  RemoveChildImpl(child, &children_);
+}
+
 }  // namespace view_manager
 }  // namespace services
 }  // namespace mojo