Google Oauth2 in embedded browser (web view)

I have a created rails application google oauth login using google ominoauth gem, it seems working fine on web.
Wrap this application in android app using webview but in android app Google login not working. it raise error :=> 403 disallowed user_agent.

please go through the link to get more details.

https://stackoverflow.com/questions/43152411/google-oauth2-in-embedded-browser-web-view

How can you wrap a rails app in android? Rails does not run under
android does it?

Colin