base: Add three helper functions to Values API.

chrome/browser/extensions/extension_webnavigation_api.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.
 
 // Implements the Chrome Extensions WebNavigation API.
 
 #include "chrome/browser/extensions/extension_webnavigation_api.h"
 
 #include "base/json/json_writer.h"
 #include "base/lazy_instance.h"
@@ skipping 581 matching lines @@
   DictionaryValue* details;
   EXTENSION_FUNCTION_VALIDATE(args_->GetDictionary(0, &details));
   DCHECK(details);
 
   int tab_id;
   int frame_id;
   EXTENSION_FUNCTION_VALIDATE(details->GetInteger(keys::kTabIdKey, &tab_id));
   EXTENSION_FUNCTION_VALIDATE(
       details->GetInteger(keys::kFrameIdKey, &frame_id));
 
-  result_.reset(Value::CreateNullValue());
+  result_.reset(base::NullValue());
 
   TabContentsWrapper* wrapper;
   if (!ExtensionTabUtil::GetTabById(
         tab_id, profile(), include_incognito(), NULL, NULL, &wrapper, NULL) ||
       !wrapper) {
     return true;
   }
 
   TabContents* tab_contents = wrapper->tab_contents();
   ExtensionWebNavigationTabObserver* observer =
@@ skipping 11 matching lines @@
   DictionaryValue* resultDict = new DictionaryValue();
   resultDict->SetString(
       keys::kUrlKey,
       frame_navigation_state.GetUrl(frame_id).spec());
   resultDict->SetBoolean(
       keys::kErrorOccurredKey,
       frame_navigation_state.GetErrorOccurredInFrame(frame_id));
   result_.reset(resultDict);
   return true;
 }