Correct const accessors in base/values.(h|cc)

chrome/common/extensions/features/feature.cc

 // Copyright (c) 2012 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/common/extensions/features/feature.h"
 
 #include <map>
 
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
@@ skipping 74 matching lines @@
   scoped_ptr<VersionInfo::Channel> channel_for_testing_;
 };
 
 static base::LazyInstance<Channel> g_channel = LAZY_INSTANCE_INITIALIZER;
 
 // TODO(aa): Can we replace all this manual parsing with JSON schema stuff?
 
 void ParseSet(const DictionaryValue* value,
               const std::string& property,
               std::set<std::string>* set) {
-  ListValue* list_value = NULL;
+  const ListValue* list_value = NULL;
   if (!value->GetList(property, &list_value))
     return;
 
   set->clear();
   for (size_t i = 0; i < list_value->GetSize(); ++i) {
     std::string str_val;
     CHECK(list_value->GetString(i, &str_val)) << property << " " << i;
     set->insert(str_val);
   }
 }
@@ skipping 264 matching lines @@
 }
 
 // static
 chrome::VersionInfo::Channel Feature::GetCurrentChannel() {
   if (g_channel_checking_enabled)
     return g_channel.Get().GetChannel();
   return chrome::VersionInfo::GetChannel();
 }
 
 }  // namespace