base: Add three helper functions to Values API.

chrome/browser/ui/webui/cookies_tree_model_adapter.cc

 // Copyright (c) 2011 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 "chrome/browser/ui/webui/cookies_tree_model_adapter.h"
 
 #include "base/memory/scoped_ptr.h"
 #include "base/string_number_conversions.h"
 #include "base/values.h"
 #include "chrome/browser/ui/webui/cookies_tree_model_util.h"
@@ skipping 110 matching lines @@
   scoped_ptr<Value> parend_id(GetTreeNodeId(model_->AsNode(parent)));
   ListValue children;
   cookies_tree_model_util::GetChildNodeList(parent, 0, parent->child_count(),
       &children);
   web_ui_->CallJavascriptFunction("ui.CookiesTree.setChildren",
       tree_id, *parend_id.get(), children);
 }
 
 Value* CookiesTreeModelAdapter::GetTreeNodeId(CookieTreeNode* node) {
   if (node == model_->GetRoot())
-    return Value::CreateNullValue();
+    return base::NullValue();
 
   return Value::CreateStringValue(
       cookies_tree_model_util::GetTreeNodeId(node));
 }