UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.62 Safari/537.36

Steps to reproduce the problem:
1. Enable 'Force users to sign-in to use the browser' setting via GPO on any given AD joined computer.
2. Users are prompted to sign in to the browser on first launch of Chrome after policy is applied

What is the expected behavior?
As designed.

What went wrong?
It would be beneficial to enforce/prefill a @domainname variable, or pass it transparently at the time of sign in through chrome://chrome-signin, which is what I presume the ForceBrowserSignIn policy summons. 

This would prevent users of AD joined machines having to their entire email address, where for the most part users are either going to have a consistent GSuite domain name. 
In cases where the domain name is different for subsets of users, for example in a K12 environment students having a different sub/secondary domain, this policy could then be altered at the OU containing those users.

Did this work before? No 

Chrome version: 71.0.3578.62  Channel: beta
OS Version: 10.0
Flash Version: 

I believe this would bring some parity to enterprise machines using Chrome with the https://www.chromium.org/administrators/policy-list-3#DeviceLoginScreenDomainAutoComplete setting currently available for ChromeOS devices.