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

Not answering your question directly (sorry), but regarding the deprecation of WebView for OAuth that you referenced: even if you find a way to avoid the WebView being detected during an OAuth flow, doing so may run contrary the Google API Services: User Data Policy, in particular the section "Do not mislead Google about an application's operating environment". So I wouldn't recommend that.

Typically using Custom Tabs for OAuth (such as via AppAuth for Android) results in a better user experiance anyway, as the user will likely already be signed-in to Google allowing them to review your request without needing to sign-in again. It's also more a more secure experiance. That's the goal of the migration – a more secure, more usable OAuth experiance for end-users :-)