Implement reordering of nodes.

Note that this doesn't apply to roots. If an app is embedded and its root node is reordered, there is no notification to the app. I figure this is up to the window manager to expose an API for this type of thing.

R=sky@chromium.org
http://crbug.com/365012

Review URL: https://codereview.chromium.org/327073003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@276768 0039d316-1c4b-4281-b951-d872f2087c98

21 files changed, 693 insertions, 40 deletions

diff --git a/mojo/examples/aura_demo/aura_demo.cc b/mojo/examples/aura_demo/aura_demo.cc
index fd87f69..d1caecc 100644
--- a/mojo/examples/aura_demo/aura_demo.cc
+++ b/mojo/examples/aura_demo/aura_demo.cc
@@ -168,6 +168,12 @@ class IViewManagerClientImpl
       uint32_t server_change_id,
       mojo::Array<view_manager::INodePtr> nodes) OVERRIDE {
   }
+  virtual void OnNodeReordered(
+      uint32_t node_id,
+      uint32_t relative_node_id,
+      view_manager::OrderDirection direction,
+      uint32_t server_change_id) OVERRIDE {
+  }
   virtual void OnNodeDeleted(uint32_t node, uint32_t server_change_id)
       OVERRIDE {
   }
diff --git a/mojo/mojo_services.gypi b/mojo/mojo_services.gypi
index 1768ccf8..ee73af1 100644
--- a/mojo/mojo_services.gypi
+++ b/mojo/mojo_services.gypi
@@ -250,6 +250,7 @@
       'type': 'static_library',
       'sources': [
         'services/public/interfaces/view_manager/view_manager.mojom',
+        'services/public/interfaces/view_manager/view_manager_constants.mojom',
       ],
       'includes': [ 'public/tools/bindings/mojom_bindings_generator.gypi' ],
       'export_dependent_settings': [
diff --git a/mojo/services/public/cpp/view_manager/lib/view_manager_synchronizer.cc b/mojo/services/public/cpp/view_manager/lib/view_manager_synchronizer.cc
index baca5a4..16e2321 100644
--- a/mojo/services/public/cpp/view_manager/lib/view_manager_synchronizer.cc
+++ b/mojo/services/public/cpp/view_manager/lib/view_manager_synchronizer.cc
@@ -246,52 +246,92 @@ class DestroyViewTreeNodeTransaction : public ViewManagerTransaction {
   DISALLOW_COPY_AND_ASSIGN(DestroyViewTreeNodeTransaction);
 };
 
-class HierarchyTransaction : public ViewManagerTransaction {
+class AddChildTransaction : public ViewManagerTransaction {
  public:
-  enum HierarchyChangeType {
-    TYPE_ADD,
-    TYPE_REMOVE
-  };
-  HierarchyTransaction(HierarchyChangeType hierarchy_change_type,
-                       Id child_id,
-                       Id parent_id,
-                       ViewManagerSynchronizer* synchronizer)
+  AddChildTransaction(Id child_id,
+                      Id parent_id,
+                      ViewManagerSynchronizer* synchronizer)
       : ViewManagerTransaction(synchronizer),
-        hierarchy_change_type_(hierarchy_change_type),
         child_id_(child_id),
         parent_id_(parent_id) {}
-  virtual ~HierarchyTransaction() {}
+  virtual ~AddChildTransaction() {}
 
  private:
   // Overridden from ViewManagerTransaction:
   virtual void DoCommit() OVERRIDE {
-    switch (hierarchy_change_type_) {
-      case TYPE_ADD:
-        service()->AddNode(
-            parent_id_,
-            child_id_,
-            GetAndAdvanceNextServerChangeId(),
-            ActionCompletedCallback());
-        break;
-      case TYPE_REMOVE:
-        service()->RemoveNodeFromParent(
-            child_id_,
-            GetAndAdvanceNextServerChangeId(),
-            ActionCompletedCallback());
-        break;
-    }
+    service()->AddNode(parent_id_,
+                       child_id_,
+                       GetAndAdvanceNextServerChangeId(),
+                       ActionCompletedCallback());
   }
 
   virtual void DoActionCompleted(bool success) OVERRIDE {
-    // TODO(beng): Failure means either one of the nodes specified didn't exist,
-    //             or we passed the same node id for both params. Roll back?
+    // TODO(beng): recovery?
   }
 
-  const HierarchyChangeType hierarchy_change_type_;
   const Id child_id_;
   const Id parent_id_;
 
-  DISALLOW_COPY_AND_ASSIGN(HierarchyTransaction);
+  DISALLOW_COPY_AND_ASSIGN(AddChildTransaction);
+};
+
+class RemoveChildTransaction : public ViewManagerTransaction {
+ public:
+  RemoveChildTransaction(Id child_id,
+                         ViewManagerSynchronizer* synchronizer)
+      : ViewManagerTransaction(synchronizer),
+        child_id_(child_id) {}
+  virtual ~RemoveChildTransaction() {}
+
+ private:
+  // Overridden from ViewManagerTransaction:
+  virtual void DoCommit() OVERRIDE {
+    service()->RemoveNodeFromParent(
+        child_id_,
+        GetAndAdvanceNextServerChangeId(),
+        ActionCompletedCallback());
+  }
+
+  virtual void DoActionCompleted(bool success) OVERRIDE {
+    // TODO(beng): recovery?
+  }
+
+  const Id child_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(RemoveChildTransaction);
+};
+
+class ReorderNodeTransaction : public ViewManagerTransaction {
+ public:
+  ReorderNodeTransaction(Id node_id,
+                         Id relative_id,
+                         OrderDirection direction,
+                         ViewManagerSynchronizer* synchronizer)
+      : ViewManagerTransaction(synchronizer),
+        node_id_(node_id),
+        relative_id_(relative_id),
+        direction_(direction) {}
+  virtual ~ReorderNodeTransaction() {}
+
+ private:
+  // Overridden from ViewManagerTransaction:
+  virtual void DoCommit() OVERRIDE {
+    service()->ReorderNode(node_id_,
+                           relative_id_,
+                           direction_,
+                           GetAndAdvanceNextServerChangeId(),
+                           ActionCompletedCallback());
+  }
+
+  virtual void DoActionCompleted(bool success) OVERRIDE {
+    // TODO(beng): recovery?
+  }
+
+  const Id node_id_;
+  const Id relative_id_;
+  const OrderDirection direction_;
+
+  DISALLOW_COPY_AND_ASSIGN(ReorderNodeTransaction);
 };
 
 class SetActiveViewTransaction : public ViewManagerTransaction {
@@ -495,20 +535,23 @@ void ViewManagerSynchronizer::AddChild(Id child_id,
                                        Id parent_id) {
   DCHECK(connected_);
   pending_transactions_.push_back(
-      new HierarchyTransaction(HierarchyTransaction::TYPE_ADD,
-                               child_id,
-                               parent_id,
-                               this));
+      new AddChildTransaction(child_id, parent_id, this));
   Sync();
 }
 
 void ViewManagerSynchronizer::RemoveChild(Id child_id, Id parent_id) {
   DCHECK(connected_);
+  pending_transactions_.push_back(new RemoveChildTransaction(child_id, this));
+  Sync();
+}
+
+void ViewManagerSynchronizer::Reorder(
+    Id node_id,
+    Id relative_node_id,
+    OrderDirection direction) {
+  DCHECK(connected_);
   pending_transactions_.push_back(
-      new HierarchyTransaction(HierarchyTransaction::TYPE_REMOVE,
-                               child_id,
-                               parent_id,
-                               this));
+      new ReorderNodeTransaction(node_id, relative_node_id, direction, this));
   Sync();
 }
 
@@ -638,7 +681,6 @@ void ViewManagerSynchronizer::OnNodeHierarchyChanged(
     Id old_parent_id,
     Id server_change_id,
     mojo::Array<INodePtr> nodes) {
-  // TODO: deal with |nodes|.
   next_server_change_id_ = server_change_id + 1;
 
   BuildNodeTree(this, nodes);
@@ -652,6 +694,19 @@ void ViewManagerSynchronizer::OnNodeHierarchyChanged(
     ViewTreeNodePrivate(old_parent).LocalRemoveChild(node);
 }
 
+void ViewManagerSynchronizer::OnNodeReordered(Id node_id,
+                                              Id relative_node_id,
+                                              OrderDirection direction,
+                                              Id server_change_id) {
+  next_server_change_id_ = server_change_id + 1;
+
+  ViewTreeNode* node = GetNodeById(node_id);
+  ViewTreeNode* relative_node = GetNodeById(relative_node_id);
+  if (node && relative_node) {
+    ViewTreeNodePrivate(node).LocalReorder(relative_node, direction);
+  }
+}
+
 void ViewManagerSynchronizer::OnNodeDeleted(Id node_id, Id server_change_id) {
   next_server_change_id_ = server_change_id + 1;
 
diff --git a/mojo/services/public/cpp/view_manager/lib/view_manager_synchronizer.h b/mojo/services/public/cpp/view_manager/lib/view_manager_synchronizer.h
index 69ebd82..f888787 100644
--- a/mojo/services/public/cpp/view_manager/lib/view_manager_synchronizer.h
+++ b/mojo/services/public/cpp/view_manager/lib/view_manager_synchronizer.h
@@ -12,6 +12,7 @@
 #include "mojo/services/public/cpp/geometry/geometry_type_converters.h"
 #include "mojo/services/public/cpp/view_manager/view_manager.h"
 #include "mojo/services/public/cpp/view_manager/view_manager_types.h"
+#include "mojo/services/public/cpp/view_manager/view_tree_node.h"
 #include "mojo/services/public/interfaces/view_manager/view_manager.mojom.h"
 
 class SkBitmap;
@@ -46,6 +47,8 @@ class ViewManagerSynchronizer : public ViewManager,
   void AddChild(Id child_id, Id parent_id);
   void RemoveChild(Id child_id, Id parent_id);
 
+  void Reorder(Id node_id, Id relative_node_id, OrderDirection direction);
+
   // Returns true if the specified node/view was created by this connection.
   bool OwnsNode(Id id) const;
   bool OwnsView(Id id) const;
@@ -106,6 +109,10 @@ class ViewManagerSynchronizer : public ViewManager,
                                       Id old_parent_id,
                                       Id server_change_id,
                                       Array<INodePtr> nodes) OVERRIDE;
+  virtual void OnNodeReordered(Id node_id,
+                               Id relative_node_id,
+                               OrderDirection direction,
+                               Id server_change_id) OVERRIDE;
   virtual void OnNodeDeleted(Id node_id, Id server_change_id) OVERRIDE;
   virtual void OnNodeViewReplaced(Id node,
                                   Id new_view_id,
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 27848a3..5a6c1d2 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
@@ -80,6 +80,72 @@ void RemoveChildImpl(ViewTreeNode* child, ViewTreeNode::Children* children) {
   }
 }
 
+class ScopedOrderChangedNotifier {
+ public:
+  ScopedOrderChangedNotifier(ViewTreeNode* node,
+                             ViewTreeNode* relative_node,
+                             OrderDirection direction)
+      : node_(node),
+        relative_node_(relative_node),
+        direction_(direction) {
+    FOR_EACH_OBSERVER(
+        ViewTreeNodeObserver,
+        *ViewTreeNodePrivate(node_).observers(),
+        OnNodeReordered(node_,
+                        relative_node_,
+                        direction_,
+                        ViewTreeNodeObserver::DISPOSITION_CHANGING));
+
+  }
+  ~ScopedOrderChangedNotifier() {
+    FOR_EACH_OBSERVER(
+        ViewTreeNodeObserver,
+        *ViewTreeNodePrivate(node_).observers(),
+        OnNodeReordered(node_,
+                        relative_node_,
+                        direction_,
+                        ViewTreeNodeObserver::DISPOSITION_CHANGED));
+  }
+
+ private:
+  ViewTreeNode* node_;
+  ViewTreeNode* relative_node_;
+  OrderDirection direction_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedOrderChangedNotifier);
+};
+
+// Returns true if the order actually changed.
+bool ReorderImpl(ViewTreeNode::Children* children,
+                 ViewTreeNode* node,
+                 ViewTreeNode* relative,
+                 OrderDirection direction) {
+  DCHECK(relative);
+  DCHECK_NE(node, relative);
+  DCHECK_EQ(node->parent(), relative->parent());
+
+  const size_t child_i =
+      std::find(children->begin(), children->end(), node) - children->begin();
+  const size_t target_i =
+      std::find(children->begin(), children->end(), relative) -
+      children->begin();
+  if ((direction == ORDER_ABOVE && child_i == target_i + 1) ||
+      (direction == ORDER_BELOW && child_i + 1 == target_i)) {
+    return false;
+  }
+
+  ScopedOrderChangedNotifier notifier(node, relative, direction);
+
+  const size_t dest_i =
+      direction == ORDER_ABOVE ?
+      (child_i < target_i ? target_i : target_i + 1) :
+      (child_i < target_i ? target_i - 1 : target_i);
+  children->erase(children->begin() + child_i);
+  children->insert(children->begin() + dest_i, node);
+
+  return true;
+}
+
 class ScopedSetActiveViewNotifier {
  public:
   ScopedSetActiveViewNotifier(ViewTreeNode* node,
@@ -238,6 +304,24 @@ void ViewTreeNode::RemoveChild(ViewTreeNode* child) {
   }
 }
 
+void ViewTreeNode::MoveToFront() {
+  Reorder(parent_->children_.back(), ORDER_ABOVE);
+}
+
+void ViewTreeNode::MoveToBack() {
+  Reorder(parent_->children_.front(), ORDER_BELOW);
+}
+
+void ViewTreeNode::Reorder(ViewTreeNode* relative, OrderDirection direction) {
+  if (!LocalReorder(relative, direction))
+    return;
+  if (manager_) {
+    static_cast<ViewManagerSynchronizer*>(manager_)->Reorder(id_,
+                                                             relative->id(),
+                                                             direction);
+  }
+}
+
 bool ViewTreeNode::Contains(ViewTreeNode* child) const {
   if (manager_)
     CHECK_EQ(ViewTreeNodePrivate(child).view_manager(), manager_);
@@ -324,6 +408,11 @@ void ViewTreeNode::LocalRemoveChild(ViewTreeNode* child) {
   RemoveChildImpl(child, &children_);
 }
 
+bool ViewTreeNode::LocalReorder(ViewTreeNode* relative,
+                                OrderDirection direction) {
+  return ReorderImpl(&parent_->children_, this, relative, direction);
+}
+
 void ViewTreeNode::LocalSetActiveView(View* view) {
   ScopedSetActiveViewNotifier notifier(this, active_view_, view);
   if (active_view_)
diff --git a/mojo/services/public/cpp/view_manager/lib/view_tree_node_private.h b/mojo/services/public/cpp/view_manager/lib/view_tree_node_private.h
index 8c8cbdd..e3b84d6 100644
--- a/mojo/services/public/cpp/view_manager/lib/view_tree_node_private.h
+++ b/mojo/services/public/cpp/view_manager/lib/view_tree_node_private.h
@@ -39,6 +39,9 @@ class ViewTreeNodePrivate {
   void LocalRemoveChild(ViewTreeNode* child) {
     node_->LocalRemoveChild(child);
   }
+  void LocalReorder(ViewTreeNode* relative, OrderDirection direction) {
+    node_->LocalReorder(relative, direction);
+  }
   void LocalSetActiveView(View* view) {
     node_->LocalSetActiveView(view);
   }
diff --git a/mojo/services/public/cpp/view_manager/tests/view_manager_unittest.cc b/mojo/services/public/cpp/view_manager/tests/view_manager_unittest.cc
index 1ce3d0a..1527cd5 100644
--- a/mojo/services/public/cpp/view_manager/tests/view_manager_unittest.cc
+++ b/mojo/services/public/cpp/view_manager/tests/view_manager_unittest.cc
@@ -250,6 +250,39 @@ void WaitForDestruction(ViewManager* view_manager,
   DoRunLoop();
 }
 
+class OrderChangeObserver : public ViewTreeNodeObserver {
+ public:
+  OrderChangeObserver(ViewTreeNode* node) : node_(node) {
+    node_->AddObserver(this);
+  }
+  virtual ~OrderChangeObserver() {
+    node_->RemoveObserver(this);
+  }
+
+ private:
+  // Overridden from ViewTreeNodeObserver:
+  virtual void OnNodeReordered(ViewTreeNode* node,
+                               ViewTreeNode* relative_node,
+                               OrderDirection direction,
+                               DispositionChangePhase phase) OVERRIDE {
+    if (phase != ViewTreeNodeObserver::DISPOSITION_CHANGED)
+      return;
+
+    DCHECK_EQ(node, node_);
+    QuitRunLoop();
+  }
+
+  ViewTreeNode* node_;
+
+  DISALLOW_COPY_AND_ASSIGN(OrderChangeObserver);
+};
+
+void WaitForOrderChange(ViewManager* view_manager,
+                        ViewTreeNode* node) {
+  OrderChangeObserver observer(node);
+  DoRunLoop();
+}
+
 // Tracks a node's destruction. Query is_valid() for current state.
 class NodeTracker : public ViewTreeNodeObserver {
  public:
@@ -709,5 +742,39 @@ TEST_F(ViewManagerTest, EmbeddingIdentity) {
   EXPECT_EQ(kWindowManagerURL, embedded->GetEmbedderURL());
 }
 
+TEST_F(ViewManagerTest, Reorder) {
+  ViewTreeNode* node1 = ViewTreeNode::Create(window_manager());
+  window_manager()->GetRoots().front()->AddChild(node1);
+
+  ViewTreeNode* node11 = ViewTreeNode::Create(window_manager());
+  node1->AddChild(node11);
+  ViewTreeNode* node12 = ViewTreeNode::Create(window_manager());
+  node1->AddChild(node12);
+
+  ViewManager* embedded = Embed(window_manager(), node1);
+
+  ViewTreeNode* node1_in_embedded = embedded->GetNodeById(node1->id());
+
+  {
+    node11->MoveToFront();
+    WaitForOrderChange(embedded, embedded->GetNodeById(node11->id()));
+
+    EXPECT_EQ(node1_in_embedded->children().front(),
+              embedded->GetNodeById(node12->id()));
+    EXPECT_EQ(node1_in_embedded->children().back(),
+              embedded->GetNodeById(node11->id()));
+  }
+
+  {
+    node11->MoveToBack();
+    WaitForOrderChange(embedded, embedded->GetNodeById(node11->id()));
+
+    EXPECT_EQ(node1_in_embedded->children().front(),
+              embedded->GetNodeById(node11->id()));
+    EXPECT_EQ(node1_in_embedded->children().back(),
+              embedded->GetNodeById(node12->id()));
+  }
+}
+
 }  // namespace view_manager
 }  // namespace mojo
diff --git a/mojo/services/public/cpp/view_manager/tests/view_tree_node_unittest.cc b/mojo/services/public/cpp/view_manager/tests/view_tree_node_unittest.cc
index 89b8293..d2326dc 100644
--- a/mojo/services/public/cpp/view_manager/tests/view_tree_node_unittest.cc
+++ b/mojo/services/public/cpp/view_manager/tests/view_tree_node_unittest.cc
@@ -348,6 +348,153 @@ TEST_F(ViewTreeNodeObserverTest, TreeChange_Reparent) {
 
 namespace {
 
+class OrderChangeObserver : public ViewTreeNodeObserver {
+ public:
+  struct Change {
+    ViewTreeNode* node;
+    ViewTreeNode* relative_node;
+    OrderDirection direction;
+    DispositionChangePhase phase;
+  };
+  typedef std::vector<Change> Changes;
+
+  explicit OrderChangeObserver(ViewTreeNode* observee) : observee_(observee) {
+    observee_->AddObserver(this);
+  }
+  virtual ~OrderChangeObserver() {
+    observee_->RemoveObserver(this);
+  }
+
+  Changes GetAndClearChanges() {
+    Changes changes;
+    changes_.swap(changes);
+    return changes;
+  }
+
+ private:
+  // Overridden from ViewTreeNodeObserver:
+  virtual void OnNodeReordered(ViewTreeNode* node,
+                               ViewTreeNode* relative_node,
+                               OrderDirection direction,
+                               DispositionChangePhase phase) OVERRIDE {
+    Change change;
+    change.node = node;
+    change.relative_node = relative_node;
+    change.direction = direction;
+    change.phase = phase;
+    changes_.push_back(change);
+  }
+
+  ViewTreeNode* observee_;
+  Changes changes_;
+
+  DISALLOW_COPY_AND_ASSIGN(OrderChangeObserver);
+};
+
+}  // namespace
+
+TEST_F(ViewTreeNodeObserverTest, Order) {
+  TestViewTreeNode v1, v11, v12, v13;
+  v1.AddChild(&v11);
+  v1.AddChild(&v12);
+  v1.AddChild(&v13);
+
+  // Order: v11, v12, v13
+  EXPECT_EQ(3U, v1.children().size());
+  EXPECT_EQ(&v11, v1.children().front());
+  EXPECT_EQ(&v13, v1.children().back());
+
+  {
+    OrderChangeObserver observer(&v11);
+
+    // Move v11 to front.
+    // Resulting order: v12, v13, v11
+    v11.MoveToFront();
+    EXPECT_EQ(&v12, v1.children().front());
+    EXPECT_EQ(&v11, v1.children().back());
+
+    OrderChangeObserver::Changes changes = observer.GetAndClearChanges();
+    EXPECT_EQ(2U, changes.size());
+    EXPECT_EQ(&v11, changes[0].node);
+    EXPECT_EQ(&v13, changes[0].relative_node);
+    EXPECT_EQ(ORDER_ABOVE, changes[0].direction);
+    EXPECT_EQ(ViewTreeNodeObserver::DISPOSITION_CHANGING, changes[0].phase);
+
+    EXPECT_EQ(&v11, changes[1].node);
+    EXPECT_EQ(&v13, changes[1].relative_node);
+    EXPECT_EQ(ORDER_ABOVE, changes[1].direction);
+    EXPECT_EQ(ViewTreeNodeObserver::DISPOSITION_CHANGED, changes[1].phase);
+  }
+
+  {
+    OrderChangeObserver observer(&v11);
+
+    // Move v11 to back.
+    // Resulting order: v11, v12, v13
+    v11.MoveToBack();
+    EXPECT_EQ(&v11, v1.children().front());
+    EXPECT_EQ(&v13, v1.children().back());
+
+    OrderChangeObserver::Changes changes = observer.GetAndClearChanges();
+    EXPECT_EQ(2U, changes.size());
+    EXPECT_EQ(&v11, changes[0].node);
+    EXPECT_EQ(&v12, changes[0].relative_node);
+    EXPECT_EQ(ORDER_BELOW, changes[0].direction);
+    EXPECT_EQ(ViewTreeNodeObserver::DISPOSITION_CHANGING, changes[0].phase);
+
+    EXPECT_EQ(&v11, changes[1].node);
+    EXPECT_EQ(&v12, changes[1].relative_node);
+    EXPECT_EQ(ORDER_BELOW, changes[1].direction);
+    EXPECT_EQ(ViewTreeNodeObserver::DISPOSITION_CHANGED, changes[1].phase);
+  }
+
+  {
+    OrderChangeObserver observer(&v11);
+
+    // Move v11 above v12.
+    // Resulting order: v12. v11, v13
+    v11.Reorder(&v12, ORDER_ABOVE);
+    EXPECT_EQ(&v12, v1.children().front());
+    EXPECT_EQ(&v13, v1.children().back());
+
+    OrderChangeObserver::Changes changes = observer.GetAndClearChanges();
+    EXPECT_EQ(2U, changes.size());
+    EXPECT_EQ(&v11, changes[0].node);
+    EXPECT_EQ(&v12, changes[0].relative_node);
+    EXPECT_EQ(ORDER_ABOVE, changes[0].direction);
+    EXPECT_EQ(ViewTreeNodeObserver::DISPOSITION_CHANGING, changes[0].phase);
+
+    EXPECT_EQ(&v11, changes[1].node);
+    EXPECT_EQ(&v12, changes[1].relative_node);
+    EXPECT_EQ(ORDER_ABOVE, changes[1].direction);
+    EXPECT_EQ(ViewTreeNodeObserver::DISPOSITION_CHANGED, changes[1].phase);
+  }
+
+  {
+    OrderChangeObserver observer(&v11);
+
+    // Move v11 below v12.
+    // Resulting order: v11, v12, v13
+    v11.Reorder(&v12, ORDER_BELOW);
+    EXPECT_EQ(&v11, v1.children().front());
+    EXPECT_EQ(&v13, v1.children().back());
+
+    OrderChangeObserver::Changes changes = observer.GetAndClearChanges();
+    EXPECT_EQ(2U, changes.size());
+    EXPECT_EQ(&v11, changes[0].node);
+    EXPECT_EQ(&v12, changes[0].relative_node);
+    EXPECT_EQ(ORDER_BELOW, changes[0].direction);
+    EXPECT_EQ(ViewTreeNodeObserver::DISPOSITION_CHANGING, changes[0].phase);
+
+    EXPECT_EQ(&v11, changes[1].node);
+    EXPECT_EQ(&v12, changes[1].relative_node);
+    EXPECT_EQ(ORDER_BELOW, changes[1].direction);
+    EXPECT_EQ(ViewTreeNodeObserver::DISPOSITION_CHANGED, changes[1].phase);
+  }
+}
+
+namespace {
+
 typedef std::vector<std::string> Changes;
 
 std::string NodeIdToString(Id id) {
diff --git a/mojo/services/public/cpp/view_manager/view_tree_node.h b/mojo/services/public/cpp/view_manager/view_tree_node.h
index d3e6ddf..2d9527c 100644
--- a/mojo/services/public/cpp/view_manager/view_tree_node.h
+++ b/mojo/services/public/cpp/view_manager/view_tree_node.h
@@ -11,6 +11,7 @@
 #include "base/observer_list.h"
 #include "mojo/public/cpp/bindings/array.h"
 #include "mojo/services/public/cpp/view_manager/view_manager_types.h"
+#include "mojo/services/public/interfaces/view_manager/view_manager_constants.mojom.h"
 #include "ui/gfx/geometry/rect.h"
 
 namespace mojo {
@@ -52,6 +53,10 @@ class ViewTreeNode {
   void AddChild(ViewTreeNode* child);
   void RemoveChild(ViewTreeNode* child);
 
+  void Reorder(ViewTreeNode* relative, OrderDirection direction);
+  void MoveToFront();
+  void MoveToBack();
+
   bool Contains(ViewTreeNode* child) const;
 
   ViewTreeNode* GetChildById(Id id);
@@ -76,6 +81,8 @@ class ViewTreeNode {
   void LocalDestroy();
   void LocalAddChild(ViewTreeNode* child);
   void LocalRemoveChild(ViewTreeNode* child);
+  // Returns true if the order actually changed.
+  bool LocalReorder(ViewTreeNode* relative, OrderDirection direction);
   void LocalSetActiveView(View* view);
   void LocalSetBounds(const gfx::Rect& old_bounds, const gfx::Rect& new_bounds);
 
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 116e156..d39f748 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
@@ -9,6 +9,8 @@
 
 #include "base/basictypes.h"
 
+#include "mojo/services/public/cpp/view_manager/view_tree_node.h"
+
 namespace gfx {
 class Rect;
 }
@@ -37,6 +39,11 @@ class ViewTreeNodeObserver {
 
   virtual void OnTreeChange(const TreeChangeParams& params) {}
 
+  virtual void OnNodeReordered(ViewTreeNode* node,
+                               ViewTreeNode* relative_node,
+                               OrderDirection direction,
+                               DispositionChangePhase phase) {}
+
   virtual void OnNodeDestroy(ViewTreeNode* node,
                              DispositionChangePhase phase) {}
 
diff --git a/mojo/services/public/interfaces/view_manager/view_manager.mojom b/mojo/services/public/interfaces/view_manager/view_manager.mojom
index df40def..e782798 100644
--- a/mojo/services/public/interfaces/view_manager/view_manager.mojom
+++ b/mojo/services/public/interfaces/view_manager/view_manager.mojom
@@ -4,6 +4,7 @@
 
 import "../geometry/geometry.mojom"
 import "../input_events/input_events.mojom"
+import "view_manager_constants.mojom"
 
 module mojo.view_manager {
 
@@ -72,6 +73,15 @@ interface IViewManager {
   RemoveNodeFromParent(uint32 node_id,
                        uint32 server_change_id) => (bool success);
 
+  // Reorders a node in its parent, relative to |relative_node_id| according to
+  // |direction|.
+  // Only the connection that created the node's parent can reorder its
+  // children.
+  ReorderNode(uint32 node_id,
+              uint32 relative_node_id,
+              OrderDirection direction,
+              uint32 server_change_id) => (bool success);
+
   // Returns the nodes comprising the tree starting at |node_id|. |node_id| is
   // the first result in the return value, unless |node_id| is invalid, in which
   // case an empty vector is returned. The nodes are visited using a depth first
@@ -148,6 +158,12 @@ interface IViewManagerClient {
                          uint32 server_change_id,
                          INode[] nodes);
 
+  // Invoked when the order of nodes within a parent changes.
+  OnNodeReordered(uint32 node_id,
+                  uint32 relative_node_id,
+                  OrderDirection direction,
+                  uint32 server_change_id);                     
+
   // Invoked when a node is deleted.
   OnNodeDeleted(uint32 node, uint32 server_change_id);
 
diff --git a/mojo/services/public/interfaces/view_manager/view_manager_constants.mojom b/mojo/services/public/interfaces/view_manager/view_manager_constants.mojom
new file mode 100644
index 0000000..5c73190
--- /dev/null
+++ b/mojo/services/public/interfaces/view_manager/view_manager_constants.mojom
@@ -0,0 +1,12 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+module mojo.view_manager {
+
+enum OrderDirection {
+  ORDER_ABOVE = 1,
+  ORDER_BELOW,
+};
+
+}
diff --git a/mojo/services/view_manager/node.cc b/mojo/services/view_manager/node.cc
index 208c9c7..cbdd16d 100644
--- a/mojo/services/view_manager/node.cc
+++ b/mojo/services/view_manager/node.cc
@@ -58,6 +58,13 @@ void Node::Remove(Node* child) {
   window_.RemoveChild(&child->window_);
 }
 
+void Node::Reorder(Node* child, Node* relative, OrderDirection direction) {
+  if (direction == ORDER_ABOVE)
+    window_.StackChildAbove(child->window(), relative->window());
+  else if (direction == ORDER_BELOW)
+    window_.StackChildBelow(child->window(), relative->window());
+}
+
 const Node* Node::GetRoot() const {
   const aura::Window* window = &window_;
   while (window && window->parent())
diff --git a/mojo/services/view_manager/node.h b/mojo/services/view_manager/node.h
index 533bc3b..bfee675 100644
--- a/mojo/services/view_manager/node.h
+++ b/mojo/services/view_manager/node.h
@@ -8,6 +8,7 @@
 #include <vector>
 
 #include "base/logging.h"
+#include "mojo/services/public/interfaces/view_manager/view_manager.mojom.h"
 #include "mojo/services/view_manager/ids.h"
 #include "mojo/services/view_manager/view_manager_export.h"
 #include "ui/aura/window.h"
@@ -37,6 +38,8 @@ class MOJO_VIEW_MANAGER_EXPORT Node
   void Add(Node* child);
   void Remove(Node* child);
 
+  void Reorder(Node* child, Node* relative, OrderDirection direction);
+
   aura::Window* window() { return &window_; }
 
   const gfx::Rect& bounds() const { return window_.bounds(); }
diff --git a/mojo/services/view_manager/root_node_manager.cc b/mojo/services/view_manager/root_node_manager.cc
index ea6cb2c..0d87d38 100644
--- a/mojo/services/view_manager/root_node_manager.cc
+++ b/mojo/services/view_manager/root_node_manager.cc
@@ -151,6 +151,17 @@ void RootNodeManager::ProcessNodeHierarchyChanged(const Node* node,
   }
 }
 
+void RootNodeManager::ProcessNodeReorder(const Node* node,
+                                         const Node* relative_node,
+                                         const OrderDirection direction) {
+  for (ConnectionMap::iterator i = connection_map_.begin();
+       i != connection_map_.end(); ++i) {
+    i->second->ProcessNodeReorder(
+        node, relative_node, direction, next_server_change_id_,
+        IsChangeSource(i->first));
+  }
+}
+
 void RootNodeManager::ProcessNodeViewReplaced(const Node* node,
                                               const View* new_view,
                                               const View* old_view) {
diff --git a/mojo/services/view_manager/root_node_manager.h b/mojo/services/view_manager/root_node_manager.h
index 93988a5..5ade95a 100644
--- a/mojo/services/view_manager/root_node_manager.h
+++ b/mojo/services/view_manager/root_node_manager.h
@@ -137,6 +137,9 @@ class MOJO_VIEW_MANAGER_EXPORT RootNodeManager : public NodeDelegate {
   void ProcessNodeHierarchyChanged(const Node* node,
                                    const Node* new_parent,
                                    const Node* old_parent);
+  void ProcessNodeReorder(const Node* node,
+                          const Node* relative_node,
+                          const OrderDirection direction);
   void ProcessNodeViewReplaced(const Node* node,
                                const View* new_view_id,
                                const View* old_view_id);
diff --git a/mojo/services/view_manager/test_change_tracker.cc b/mojo/services/view_manager/test_change_tracker.cc
index 133c171..4260edd 100644
--- a/mojo/services/view_manager/test_change_tracker.cc
+++ b/mojo/services/view_manager/test_change_tracker.cc
@@ -26,6 +26,10 @@ std::string RectToString(const gfx::Rect& rect) {
                             rect.height());
 }
 
+std::string DirectionToString(OrderDirection direction) {
+  return direction == ORDER_ABOVE ? "above" : "below";
+}
+
 std::string ChangeToDescription1(const Change& change) {
   switch (change.type) {
     case CHANGE_TYPE_CONNECTION_ESTABLISHED:
@@ -55,6 +59,14 @@ std::string ChangeToDescription1(const Change& change) {
             NodeIdToString(change.node_id2).c_str(),
             NodeIdToString(change.node_id3).c_str());
 
+    case CHANGE_TYPE_NODE_REORDERED:
+      return base::StringPrintf(
+          "Reordered change_id=%d node=%s relative=%s direction=%s",
+          static_cast<int>(change.change_id),
+          NodeIdToString(change.node_id).c_str(),
+          NodeIdToString(change.node_id2).c_str(),
+          DirectionToString(change.direction).c_str());
+
     case CHANGE_TYPE_NODE_DELETED:
       return base::StringPrintf("NodeDeleted change_id=%d node=%s",
                                 static_cast<int>(change.change_id),
@@ -119,7 +131,8 @@ Change::Change()
       node_id3(0),
       view_id(0),
       view_id2(0),
-      event_action(0) {}
+      event_action(0),
+      direction(ORDER_ABOVE) {}
 
 Change::~Change() {
 }
@@ -185,6 +198,19 @@ void TestChangeTracker::OnNodeHierarchyChanged(Id node_id,
   AddChange(change);
 }
 
+void TestChangeTracker::OnNodeReordered(Id node_id,
+                                        Id relative_node_id,
+                                        OrderDirection direction,
+                                        Id server_change_id) {
+  Change change;
+  change.type = CHANGE_TYPE_NODE_REORDERED;
+  change.node_id = node_id;
+  change.node_id2 = relative_node_id;
+  change.direction = direction;
+  change.change_id = server_change_id;
+  AddChange(change);
+}
+
 void TestChangeTracker::OnNodeDeleted(Id node_id, Id server_change_id) {
   Change change;
   change.type = CHANGE_TYPE_NODE_DELETED;
diff --git a/mojo/services/view_manager/test_change_tracker.h b/mojo/services/view_manager/test_change_tracker.h
index ef0c002..fbea61d 100644
--- a/mojo/services/view_manager/test_change_tracker.h
+++ b/mojo/services/view_manager/test_change_tracker.h
@@ -23,6 +23,7 @@ enum ChangeType {
   CHANGE_TYPE_SERVER_CHANGE_ID_ADVANCED,
   CHANGE_TYPE_NODE_BOUNDS_CHANGED,
   CHANGE_TYPE_NODE_HIERARCHY_CHANGED,
+  CHANGE_TYPE_NODE_REORDERED,
   CHANGE_TYPE_NODE_DELETED,
   CHANGE_TYPE_VIEW_DELETED,
   CHANGE_TYPE_VIEW_REPLACED,
@@ -57,6 +58,7 @@ struct Change {
   gfx::Rect bounds2;
   int32 event_action;
   String creator_url;
+  OrderDirection direction;
 };
 
 // Converts Changes to string descriptions.
@@ -106,6 +108,10 @@ class TestChangeTracker {
                               Id old_parent_id,
                               Id server_change_id,
                               Array<INodePtr> nodes);
+  void OnNodeReordered(Id node_id,
+                       Id relative_node_id,
+                       OrderDirection direction,
+                       Id server_change_id);
   void OnNodeDeleted(Id node_id, Id server_change_id);
   void OnViewDeleted(Id view_id);
   void OnNodeViewReplaced(Id node_id, Id new_view_id, Id old_view_id);
diff --git a/mojo/services/view_manager/view_manager_connection.cc b/mojo/services/view_manager/view_manager_connection.cc
index 8d4d0a6..0c724bd 100644
--- a/mojo/services/view_manager/view_manager_connection.cc
+++ b/mojo/services/view_manager/view_manager_connection.cc
@@ -170,6 +170,23 @@ void ViewManagerConnection::ProcessNodeHierarchyChanged(
                                    NodesToINodes(to_send));
 }
 
+void ViewManagerConnection::ProcessNodeReorder(const Node* node,
+                                               const Node* relative_node,
+                                               OrderDirection direction,
+                                               Id server_change_id,
+                                               bool originated_change) {
+  if (originated_change ||
+      !known_nodes_.count(NodeIdToTransportId(node->id())) ||
+      !known_nodes_.count(NodeIdToTransportId(relative_node->id()))) {
+    return;
+  }
+
+  client()->OnNodeReordered(NodeIdToTransportId(node->id()),
+                            NodeIdToTransportId(relative_node->id()),
+                            direction,
+                            server_change_id);
+}
+
 void ViewManagerConnection::ProcessNodeViewReplaced(
     const Node* node,
     const View* new_view,
@@ -267,6 +284,36 @@ bool ViewManagerConnection::CanAddNode(const Node* parent,
   return (IsNodeDescendantOfRoots(child) || child->id().connection_id == id_);
 }
 
+bool ViewManagerConnection::CanReorderNode(const Node* node,
+                                           const Node* relative_node,
+                                           OrderDirection direction) const {
+  if (!node || !relative_node)
+    return false;
+
+  if (node->id().connection_id != id_)
+    return false;
+
+  const Node* parent = node->GetParent();
+  if (!parent || parent != relative_node->GetParent())
+    return false;
+
+  if (known_nodes_.count(NodeIdToTransportId(parent->id())) == 0)
+    return false;
+
+  std::vector<const Node*> children = parent->GetChildren();
+  const size_t child_i =
+      std::find(children.begin(), children.end(), node) - children.begin();
+  const size_t target_i =
+      std::find(children.begin(), children.end(), relative_node) -
+      children.begin();
+  if ((direction == ORDER_ABOVE && child_i == target_i + 1) ||
+      (direction == ORDER_BELOW && child_i + 1 == target_i)) {
+    return false;
+  }
+
+  return true;
+}
+
 bool ViewManagerConnection::CanDeleteNode(const NodeId& node_id) const {
   return node_id.connection_id == id_;
 }
@@ -553,6 +600,27 @@ void ViewManagerConnection::RemoveNodeFromParent(
   callback.Run(success);
 }
 
+void ViewManagerConnection::ReorderNode(Id node_id,
+                                        Id relative_node_id,
+                                        OrderDirection direction,
+                                        Id server_change_id,
+                                        const Callback<void(bool)>& callback) {
+  bool success = false;
+  if (server_change_id == root_node_manager_->next_server_change_id()) {
+    Node* node = GetNode(NodeIdFromTransportId(node_id));
+    Node* relative_node = GetNode(NodeIdFromTransportId(relative_node_id));
+    if (CanReorderNode(node, relative_node, direction)) {
+      success = true;
+      RootNodeManager::ScopedChange change(
+          this, root_node_manager_,
+          RootNodeManager::CHANGE_TYPE_ADVANCE_SERVER_CHANGE_ID, false);
+      node->GetParent()->Reorder(node, relative_node, direction);
+      root_node_manager_->ProcessNodeReorder(node, relative_node, direction);
+    }
+  }
+  callback.Run(success);
+}
+
 void ViewManagerConnection::GetNodeTree(
     Id node_id,
     const Callback<void(Array<INodePtr>)>& callback) {
diff --git a/mojo/services/view_manager/view_manager_connection.h b/mojo/services/view_manager/view_manager_connection.h
index b9eae90..b2f326b 100644
--- a/mojo/services/view_manager/view_manager_connection.h
+++ b/mojo/services/view_manager/view_manager_connection.h
@@ -86,6 +86,11 @@ class MOJO_VIEW_MANAGER_EXPORT ViewManagerConnection
                                    const Node* old_parent,
                                    Id server_change_id,
                                    bool originated_change);
+  void ProcessNodeReorder(const Node* node,
+                          const Node* relative_node,
+                          OrderDirection direction,
+                          Id server_change_id,
+                          bool originated_change);
   void ProcessNodeViewReplaced(const Node* node,
                                const View* new_view,
                                const View* old_view,
@@ -110,6 +115,9 @@ class MOJO_VIEW_MANAGER_EXPORT ViewManagerConnection
   // for this connection.
   bool CanRemoveNodeFromParent(const Node* node) const;
   bool CanAddNode(const Node* parent, const Node* child) const;
+  bool CanReorderNode(const Node* node,
+                      const Node* relative_node,
+                      OrderDirection direction) const;
   bool CanDeleteNode(const NodeId& node_id) const;
   bool CanDeleteView(const ViewId& view_id) const;
   bool CanSetView(const Node* node, const ViewId& view_id) const;
@@ -170,6 +178,11 @@ class MOJO_VIEW_MANAGER_EXPORT ViewManagerConnection
       Id node_id,
       Id server_change_id,
       const Callback<void(bool)>& callback) OVERRIDE;
+  virtual void ReorderNode(Id node_id,
+                           Id relative_node_id,
+                           OrderDirection direction,
+                           Id server_change_id,
+                           const Callback<void(bool)>& callback) OVERRIDE;
   virtual void GetNodeTree(
       Id node_id,
       const Callback<void(Array<INodePtr>)>& callback) OVERRIDE;
diff --git a/mojo/services/view_manager/view_manager_connection_unittest.cc b/mojo/services/view_manager/view_manager_connection_unittest.cc
index 4f5d1c9..d9280d8 100644
--- a/mojo/services/view_manager/view_manager_connection_unittest.cc
+++ b/mojo/services/view_manager/view_manager_connection_unittest.cc
@@ -22,6 +22,7 @@
 #include "mojo/services/public/cpp/view_manager/util.h"
 #include "mojo/services/public/cpp/view_manager/view_manager_types.h"
 #include "mojo/services/public/interfaces/view_manager/view_manager.mojom.h"
+#include "mojo/services/view_manager/ids.h"
 #include "mojo/services/view_manager/test_change_tracker.h"
 #include "mojo/shell/shell_test_helper.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -112,6 +113,19 @@ class ViewManagerProxy : public TestChangeTracker::Delegate {
     RunMainLoop();
     return result;
   }
+  bool ReorderNode(Id node_id,
+                   Id relative_node_id,
+                   OrderDirection direction,
+                   Id server_change_id) {
+    changes_.clear();
+    bool result = false;
+    view_manager_->ReorderNode(node_id, relative_node_id, direction,
+                               server_change_id,
+                               base::Bind(&ViewManagerProxy::GotResult,
+                                          base::Unretained(this), &result));
+    RunMainLoop();
+    return result;
+  }
   bool SetView(Id node_id, Id view_id) {
     changes_.clear();
     bool result = false;
@@ -305,6 +319,13 @@ class TestViewManagerClientConnection
     tracker_.OnNodeHierarchyChanged(node, new_parent, old_parent,
                                     server_change_id, nodes.Pass());
   }
+  virtual void OnNodeReordered(Id node_id,
+                               Id relative_node_id,
+                               OrderDirection direction,
+                               Id server_change_id) OVERRIDE {
+    tracker_.OnNodeReordered(node_id, relative_node_id, direction,
+                             server_change_id);
+  }
   virtual void OnNodeDeleted(Id node, Id server_change_id) OVERRIDE {
     tracker_.OnNodeDeleted(node, server_change_id);
   }
@@ -758,6 +779,84 @@ TEST_F(ViewManagerConnectionTest, NodeHierarchyChangedAddingKnownToUnknown) {
   }
 }
 
+TEST_F(ViewManagerConnectionTest, ReorderNode) {
+  Id node1_id = BuildNodeId(1, 1);
+  Id node2_id = BuildNodeId(1, 2);
+  Id node3_id = BuildNodeId(1, 3);
+  Id node4_id = BuildNodeId(1, 4);  // Peer to 1,1
+  Id node5_id = BuildNodeId(1, 5);  // Peer to 1,1
+  Id node6_id = BuildNodeId(1, 6);  // Child of 1,2.
+  Id node7_id = BuildNodeId(1, 7);  // Unparented.
+  Id node8_id = BuildNodeId(1, 8);  // Unparented.
+  ASSERT_TRUE(connection_->CreateNode(node1_id));
+  ASSERT_TRUE(connection_->CreateNode(node2_id));
+  ASSERT_TRUE(connection_->CreateNode(node3_id));
+  ASSERT_TRUE(connection_->CreateNode(node4_id));
+  ASSERT_TRUE(connection_->CreateNode(node5_id));
+  ASSERT_TRUE(connection_->CreateNode(node6_id));
+  ASSERT_TRUE(connection_->CreateNode(node7_id));
+  ASSERT_TRUE(connection_->CreateNode(node8_id));
+  ASSERT_TRUE(connection_->AddNode(node1_id, node2_id, 1));
+  ASSERT_TRUE(connection_->AddNode(node2_id, node6_id, 2));
+  ASSERT_TRUE(connection_->AddNode(node1_id, node3_id, 3));
+  ASSERT_TRUE(connection_->AddNode(
+      NodeIdToTransportId(RootNodeId()), node4_id, 4));
+  ASSERT_TRUE(connection_->AddNode(
+      NodeIdToTransportId(RootNodeId()), node5_id, 5));
+
+  ASSERT_NO_FATAL_FAILURE(EstablishSecondConnection(false));
+
+  {
+    connection_->ReorderNode(node2_id, node3_id, ORDER_ABOVE, 6);
+
+    connection2_->DoRunLoopUntilChangesCount(1);
+    const Changes changes(ChangesToDescription1(connection2_->changes()));
+    ASSERT_EQ(1u, changes.size());
+    EXPECT_EQ(
+        "Reordered change_id=6 node=1,2 relative=1,3 direction=above",
+        changes[0]);
+  }
+
+  {
+    connection_->ReorderNode(node2_id, node3_id, ORDER_BELOW, 7);
+
+    connection2_->DoRunLoopUntilChangesCount(1);
+    const Changes changes(ChangesToDescription1(connection2_->changes()));
+    ASSERT_EQ(1u, changes.size());
+    EXPECT_EQ(
+        "Reordered change_id=7 node=1,2 relative=1,3 direction=below",
+        changes[0]);
+  }
+
+  {
+    // node2 is already below node3.
+    EXPECT_FALSE(connection_->ReorderNode(node2_id, node3_id, ORDER_BELOW, 8));
+  }
+
+  {
+    // node4 & 5 are unknown to connection2_.
+    EXPECT_FALSE(connection2_->ReorderNode(node4_id, node5_id, ORDER_ABOVE, 8));
+  }
+
+  {
+    // node6 & node3 have different parents.
+    EXPECT_FALSE(connection_->ReorderNode(node3_id, node6_id, ORDER_ABOVE, 8));
+  }
+
+  {
+    // Non-existent node-ids
+    EXPECT_FALSE(connection_->ReorderNode(BuildNodeId(1, 27),
+                                          BuildNodeId(1, 28),
+                                          ORDER_ABOVE,
+                                          8));
+  }
+
+  {
+    // node7 & node8 are un-parented.
+    EXPECT_FALSE(connection_->ReorderNode(node7_id, node8_id, ORDER_ABOVE, 8));
+  }
+}
+
 // Verifies DeleteNode works.
 TEST_F(ViewManagerConnectionTest, DeleteNode) {
   ASSERT_TRUE(connection_->CreateNode(BuildNodeId(1, 2)));