Upcoming change to Chrome will "break" some SAML SPs

Google is planning to introduce a change to how Chrome treats third party cookies by default:

https://blog.chromium.org/2019/05/improving-privacy-and-security-on-web.html

This change will cause issues with some SAML service providers that depend on a cookie to correlate a SAML response to a user session.

Further details are available via the following links:

https://chromestatus.com/feature/5088147346030592
https://web.dev/samesite-cookies-explained
https://tools.ietf.org/html/draft-west-cookie-incrementalism-00

A complication is that the recommended fix of setting SameSite=none on the cookie(s) will break browsers on Mac and iOS because of a different bug:

https://bugs.webkit.org/show_bug.cgi?id=198181

Relying parties can test to see if they are impacted as follows:

1. Download the Chrome 76 beta (https://www.google.com/chrome/beta/)
2. Open "chrome://flags/" and set the experimental "SameSite by default cookies" flag to "Enabled".
3. Try to log in to your SP from both GCKey and CBS..

I've already confirmed that both the OpenAM fedlets for Java and.NET are affected. Hoping that RPs using other software can share the results of their testing.

Start with the Chrome 76 beta and enable the “SameSite by default cookies” flag in chrome://flags/. Test login to the service provider from both GCKey and CBS, checking the linked SameSite cookie and WebKit details. Done means recording whether the relying party is affected and sharing the result, including the OpenAM Java and .NET cases.

Written by the indexing model from the issue text.