Next month Google will be updating the smartphone user-agent of Googlebot:
Reviewing the code-base it doesn’t look like it’s going to make a blindest bit of difference to Discourse.
Someone might possibily want to add the new user-agent here:
https://github.com/discourse/discourse/blob/master/spec/components/crawler_detection_spec.rb
Current Googlebot smartphone user-agent:
Mozilla/5.0 (iPhone; CPU iPhone OS 8_3 like Mac OS X) AppleWebKit/600.1.4 (KHTML, like Gecko) Version/8.0 Mobile/12F70 Safari/600.1.4 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)
Googlebot smartphone user-agent starting from April 18, 2016:
Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5X Build/MMB29P) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.96 Mobile Safari/537.36 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)