[PrivacyBadger] Tracking warnings for sites

[Don Marti]

There are many reasons for a legit site to encourage
users to install a tracking protection tool.
For example, an ad-supported original content site
can benefit by making it harder to track its valuable
audience to less expensive sites.

For most users on most browsers, though, third-party
tracking is hard to spot.  Sites can help with a
little bit of third-party JavaScript.

Experiment with a tracking warning system:
  http://ad.aloodo.com/

The general idea is: add an iframe on the page and try
a tracking cookie within the iframe.  If site-to-site
tracking succeeds, send a message to the containing
page, which can put up a notification, or implement a
lightweight, easy to bypass, "reverse tracking wall"
on a page (hide content or redirect if tracking
has succeded).

Comments, suggestions, pull requests welcome.

-- 
Don Marti                    
http://zgp.org/~dmarti/
dmarti at zgp.org