As of April 20, 2017, Google no longer allows OAuth requests to Google in embedded browsers known as "web-views", such as the WebView UI element on Android and UIWebView/WKWebView on iOS, and equivalents on Windows and OS X. It blocks OAuth requests using web-views for all OAuth clients on platforms where viable alternatives exist.
Steps to Reproduce
Set up an SSO provider that uses Google OAuth as its authentication (for example, PING).
For more information, see the product documentation topic OAuth 2.0.
Set up the primary IdP to this SSO record.
For more information, see the product documentation topic Identity Provider (IdP) system properties.
Try to log in to the instance using the Google OAuth authentication.
Note that Google will block the request.
If you need to log in using mobile applications, avoid using Google OAuth or configure your internal Authentication to avoid using "web-views" on Google OAuth. Users facing this problem need to log in using the desktop version.
Related Problem: PRB994306