base: Add three helper functions to Values API.

chrome/browser/ui/webui/options/core_options_handler.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/options/core_options_handler.h"
 
 #include "base/json/json_reader.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/string16.h"
 #include "base/string_number_conversions.h"
@@ skipping 139 matching lines @@
   DCHECK(handlers_host_);
   handlers_host_->InitializeHandlers();
 }
 
 Value* CoreOptionsHandler::FetchPref(const std::string& pref_name) {
   PrefService* pref_service = Profile::FromWebUI(web_ui_)->GetPrefs();
 
   const PrefService::Preference* pref =
       pref_service->FindPreference(pref_name.c_str());
   if (!pref)
-    return Value::CreateNullValue();
+    return base::NullValue();
 
   return CreateValueForPref(pref);
 }
 
 void CoreOptionsHandler::ObservePref(const std::string& pref_name) {
   registrar_.Add(pref_name.c_str(), this);
 }
 
 void CoreOptionsHandler::SetPref(const std::string& pref_name,
                                  const Value* value,
@@ skipping 220 matching lines @@
     const std::wstring& callback_function = iter->second;
     ListValue result_value;
     result_value.Append(Value::CreateStringValue(pref_name->c_str()));
 
     result_value.Append(CreateValueForPref(pref));
 
     web_ui_->CallJavascriptFunction(WideToASCII(callback_function),
                                     result_value);
   }
 }