A new flag added to Chrome v41, currently in beta, reduces the information about referring websites shared with others as you browse the web. The default behavior, without the flag enabled, is to pass along the website you clicked from when you browse to a new page. This feature will make the referring information sent along to websites less specific when you go from one domain to another.
Knowing your referring website can reveal a fair amount of information about you. At the basic level, anything about the site you clicked from can be used to learn something. If you came to Android Police from www.ILikePonies.com, we are going to assume that you like ponies. But what if you came from www.ILikePonies.com/PoniesAreAttractiveToMe.html? Now we know something totally different about you.
Now, suppose you were assigned a unique identifier by your referring website. You might send us the following as your referrer: www.ILikePonies.com/PoniesAreAttractiveToMe/j6oAOxCWZh/CD723LGeXlf. We could potentially spoof your session on the referring site if they don't have good security. Or, more likely, third-party ad servers like Google could track your information across the web even if you have taken other privacy-friendly measures like the recently-implemented disable third party cookies feature in mobile Chrome.
This flag will strip some of that identifying information out of the HTTP header, particularly when you're moving from one website to another. Rather than revealing session identifiers or search queries through your referrer, the website will get more general information such as the root domain or nothing at all. Some web pages may break with this feature enabled if they are searching for hotlinks and the like.