[NTP Snippets] Cleanups from clang-tidy

components/ntp_snippets/category_info.cc

 // Copyright 2016 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 "components/ntp_snippets/category_info.h"
 
 namespace ntp_snippets {
 
 CategoryInfo::CategoryInfo(const base::string16& title,
                            ContentSuggestionsCardLayout card_layout,
                            bool has_more_button,
                            bool show_if_empty)
     : title_(title),
       card_layout_(card_layout),
       has_more_button_(has_more_button),
       show_if_empty_(show_if_empty) {}
 
-CategoryInfo::~CategoryInfo() {}
+CategoryInfo::~CategoryInfo() = default;
 
 }  // namespace ntp_snippets