> Chrome never implemented RSS auto discovery.
The Chrome team argues that not enough people use RSS to justify having an icon in the URL bar by default. I personally think this is somewhat circular reasoning ("People don't use RSS, so we won't show an icon letting them know about RSS"), but sadly other browsers such as Firefox have followed their lead and removed RSS notifications by default.
Also, whether or not the browser implements native RSS auto-discovery is irrelevant to the point of the article. The Chrome extension in the article could be easily implemented by checking for a special <link> element, so that no URLs need to be sent back to Google just to know that the page is Plus-enabled.
However, off the top of my head, there's a good reason why this wouldn't do much good. The advertised functionality of the Google+ extension requires details about the Google+ stream that the page links to. If the extension checked for a <link>, it would still need to send the URL in that link to Google to get those stream details. The privacy improvement seems marginal.
In the end, I think this complaint is better served by declaring that the URLs aren't recorded. Google's DNS and Omnibox already have similar declarations, so it wouldn't be unprecedented.