Chrome 63+ update for captive portal detection

[Austin Sasko]

In chrome 63 and above, Chrome now attempts to determine if a device is behind a network that requires captive portal redirection/authentication. When it determines that the network it is on, it displays the page below. 

What triggers Chrome attempting to check if an end device is behind a captive portal, and what technical steps does it use to determine that it is behind a captive portal in order to show the aforementioned page? (I have gathered that at least one potential trigger is when reaching a public IP address and getting an SSL error about a hostname mismatch)