Run clang-modernize -use-nullptr over src/extensions/.

extensions/common/message_bundle.cc

Index: extensions/common/message_bundle.cc
diff --git a/extensions/common/message_bundle.cc b/extensions/common/message_bundle.cc
index 1340e549935fade3a68f2e70dcdeac801982974e..6641eee295e03f796cf2aaa75516f2e0be87d5f1 100644
--- a/extensions/common/message_bundle.cc
+++ b/extensions/common/message_bundle.cc
@@ -62,7 +62,7 @@ MessageBundle* MessageBundle::Create(const CatalogVector& locale_catalogs,
                                      std::string* error) {
   scoped_ptr<MessageBundle> message_bundle(new MessageBundle);
   if (!message_bundle->Init(locale_catalogs, error))
-    return NULL;
+    return nullptr;
 
   return message_bundle.release();
 }
@@ -338,7 +338,7 @@ L10nMessagesMap* GetL10nMessagesMap(const std::string& extension_id) {
   if (it != g_extension_to_messages_map.Get().messages_map.end())
     return &(it->second);
 
-  return NULL;
+  return nullptr;
 }
 
 void EraseL10nMessagesMap(const std::string& extension_id) {