Rewrite scoped_ptr<T>(NULL) to use the default ctor in chrome/.

chrome/browser/extensions/menu_manager.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/browser/extensions/menu_manager.h"
 
 #include <algorithm>
 
 #include "base/json/json_writer.h"
 #include "base/logging.h"
@@ skipping 103 matching lines @@
                    const std::string& title,
                    bool checked,
                    bool enabled,
                    Type type,
                    const ContextList& contexts)
     : id_(id),
       title_(title),
       type_(type),
       checked_(checked),
       enabled_(enabled),
-      contexts_(contexts),
-      parent_id_(0) {
-}
+      contexts_(contexts) {}
 
 MenuItem::~MenuItem() {
   STLDeleteElements(&children_);
 }
 
 MenuItem* MenuItem::ReleaseChild(const Id& child_id,
                                  bool recursive) {
   for (List::iterator i = children_.begin(); i != children_.end(); ++i) {
     MenuItem* child = NULL;
     if ((*i)->id() == child_id) {
@@ skipping 725 matching lines @@
       if (uid < other.uid)
         return true;
       if (uid == other.uid)
         return string_uid < other.string_uid;
     }
   }
   return false;
 }
 
 }  // namespace extensions