Aura-powered Opera 21 for desktop computers released today - Opera Desktop
ブラウザ ID
Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/34.0.1847.132 Safari/537.36 OPR/21.0.1432.57
Google Chrome 安定版は Windows が 34.0.1847.131、Mac/Linux が 34.0.1847.132。
5/7 追記
Security changes in Opera 21 - Opera Security