Trigger Node destruction notifications from Node's dtor

mojo/services/view_manager/node.cc

 // 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.
 
 #include "mojo/services/view_manager/node.h"
 
 #include "mojo/services/view_manager/node_delegate.h"
 #include "mojo/services/view_manager/view.h"
 #include "ui/aura/window_property.h"
 #include "ui/base/cursor/cursor.h"
@@ skipping 19 matching lines @@
   window_.set_owned_by_parent(false);
   window_.AddObserver(this);
   window_.SetProperty(kNodeKey, this);
   window_.Init(aura::WINDOW_LAYER_TEXTURED);
 
   // TODO(sky): this likely needs to be false and add a visibility API.
   window_.Show();
 }
 
 Node::~Node() {
-  SetView(NULL);
   // This is implicitly done during deletion of the window, but we do it here so
   // that we're in a known state.
   if (window_.parent())
     window_.parent()->RemoveChild(&window_);
+
+  // This must be done *after* updating the hierarchy since the hierarchy change
+  // will remove the node from the connections that know about it, preventing
+  // this notification from being sent after the destruction notification.
+  SetView(NULL);
+
+  delegate_->OnNodeDestroyed(this);
 }
 
 // static
 Node* Node::NodeForWindow(aura::Window* window) {
   return window->GetProperty(kNodeKey);
 }
 
 const Node* Node::GetParent() const {
   if (!window_.parent())
     return NULL;
@@ skipping 71 matching lines @@
 }
 
 void Node::OnWindowHierarchyChanged(
     const aura::WindowObserver::HierarchyChangeParams& params) {
   if (params.target != &window_ || params.receiver != &window_)
     return;
   const Node* new_parent = params.new_parent ?
       params.new_parent->GetProperty(kNodeKey) : NULL;
   const Node* old_parent = params.old_parent ?
       params.old_parent->GetProperty(kNodeKey) : NULL;
-  delegate_->OnNodeHierarchyChanged(this, new_parent, old_parent);
+  // This check is needed because even the root Node's aura::Window has a
+  // parent, but the Node itself has no parent (so it's possible for us to
+  // receive this notification from aura when no logical Node hierarchy change
+  // has actually ocurred).
+  if (new_parent != old_parent)
+    delegate_->OnNodeHierarchyChanged(this, new_parent, old_parent);
 }
 
 gfx::Size Node::GetMinimumSize() const {
   return gfx::Size();
 }
 
 gfx::Size Node::GetMaximumSize() const {
   return gfx::Size();
 }
 
@@ skipping 50 matching lines @@
 }
 
 void Node::OnEvent(ui::Event* event) {
   if (view_)
     delegate_->OnViewInputEvent(view_, event);
 }
 
 }  // namespace service
 }  // namespace view_manager
 }  // namespace mojo