Hi,
The browser signature can be calculated based on a combination of several things : user agent string, operating system, IP, screen resolution, cookies, preferred language, time zone, plugins installed, graphic card...
There's is no official formula to calculate the "browser signature" and as you can see in the sources, there is no "id" in CEF4Delphi.
Try this website to check how unique is your web browser :
https://amiunique.org
Read this for more info about your browser fingerprint :
https://en.wikipedia.org/wiki/Device_fingerprint