Add test for ash devtools DOM agent getDocument method

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"
 
 namespace ash {
 namespace devtools {
 
 namespace {
 using namespace ui::devtools::protocol;
 
 std::unique_ptr<DOM::Node> BuildNode(
     const std::string& name,
     std::unique_ptr<Array<std::string>> attributes,
     std::unique_ptr<Array<DOM::Node>> children) {
   static DOM::NodeId node_ids = 0;
   constexpr int kDomElementNodeType = 1;
-  return DOM::Node::create()
-      .setNodeId(node_ids++)
-      .setNodeName(name)
-      .setNodeType(kDomElementNodeType)
-      .setAttributes(std::move(attributes))
-      .setChildNodeCount(children->length())
-      .setChildren(std::move(children))
-      .build();
+  std::unique_ptr<DOM::Node> node = DOM::Node::create()
+                                        .setNodeId(node_ids++)
+                                        .setNodeName(name)
+                                        .setNodeType(kDomElementNodeType)
+                                        .setAttributes(std::move(attributes))
+                                        .build();
+  node->setChildNodeCount(children->length());
+  node->setChildren(std::move(children));
+  return node;
 }
 
 std::unique_ptr<Array<std::string>> GetAttributes(const ash::WmWindow* window) {
   std::unique_ptr<Array<std::string>> attributes = Array<std::string>::create();
   attributes->addItem("name");
   attributes->addItem(window->GetName());
   attributes->addItem("active");
   attributes->addItem(window->IsActive() ? "true" : "false");
   return attributes;
 }
@@ skipping 65 matching lines @@
 }
 
 ui::devtools::protocol::Response AshDevToolsDOMAgent::getDocument(
     std::unique_ptr<ui::devtools::protocol::DOM::Node>* out_root) {
   *out_root = BuildInitialTree();
   return ui::devtools::protocol::Response::OK();
 }
 
 }  // namespace devtools
 }  // namespace ash