It is an White Flat Theme for One Sms - New 6.0 Emoji message app, Love it!About the One SMS:
One SMS is an Material Design look sms app. Share more emojis with friends, Send group texts, your favorite pictures, videos, Gifs and even audio messages to your contacts.
Key features:• Flat/Beautiful: Latest Material Design UI, Running smoothly and support your own custom.
• Fast: Search any text in all conversation thread, Select or take pictures directly from the app and send easily to your contacts, compose new message quickly.
• Simple: an internal Emoji keyboard support and easy to use, Support batch delete in conversation list and thread, Slide right to delete or call contact.