How can Google detect a request is from a WebView?

Question

Google announced that they \"will no longer allow OAuth requests to Google in embedded browsers known as \'web-views\'\".

In Android, requests from WebViews get

Answer 1

I don't think Google is planning to enforce any sort of violent detection of WebViews, I think the policy change is just meant to start a new norm. Google does not have to enforce it, if it becomes the norm, users will find it shady that an app proposes sign-in through an embedded browser---and users will require compliance. (I am not saying every user of an app has to make such requests, but I'm betting there is, for any app that matters at least one vocal one.)