Update ash DOM agent so that widgets are direct children of windows

ash/common/devtools/ash_devtools_dom_agent.cc

 // Copyright 2016 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 "ash/common/devtools/ash_devtools_dom_agent.h"
 
 #include "ash/common/wm_window.h"
 #include "components/ui_devtools/devtools_server.h"
 #include "ui/views/view.h"
 #include "ui/views/widget/widget.h"
@@ skipping 111 matching lines @@
 }
 
 void AshDevToolsDOMAgent::OnWindowStackingChanged(WmWindow* window) {
   RemoveWindowNode(window, window->GetParent());
   AddWindowNode(window);
 }
 
 std::unique_ptr<DOM::Node> AshDevToolsDOMAgent::BuildTreeForWindow(
     ash::WmWindow* window) {
   std::unique_ptr<Array<DOM::Node>> children = Array<DOM::Node>::create();
+  views::Widget* widget = window->GetInternalWidget();
+  if (widget)
+    children->addItem(BuildTreeForRootWidget(widget));
   for (ash::WmWindow* child : window->GetChildren()) {
     children->addItem(BuildTreeForWindow(child));
-    views::Widget* widget = child->GetInternalWidget();
-    if (widget)
-      children->addItem(BuildTreeForRootWidget(widget));
   }
   std::unique_ptr<ui::devtools::protocol::DOM::Node> node =
       BuildNode("Window", GetAttributes(window), std::move(children));
   // Only add as observer if window is not in map
   if (!window_to_node_id_map_.count(window))
     window->AddObserver(this);
   window_to_node_id_map_[window] = node->getNodeId();
   return node;
 }
 
@@ skipping 33 matching lines @@
 }
 
 void AshDevToolsDOMAgent::Reset() {
   RemoveObserverFromAllWindows();
   window_to_node_id_map_.clear();
   node_ids = 1;
 }
 
 }  // namespace devtools
 }  // namespace ash