You can read the paper here.

This paper is the last artifact of my work at Mozilla, since I left employment there at the beginning of April. I believe that Mozilla can make progress in privacy, but leadership needs to recognize that current advertising practices that enable “free” content are in direct conflict with security, privacy, stability, and performance concerns — and that Firefox is first and foremost a user-agent, not an industry-agent.

Source: Monica at Mozilla: Tracking Protection for Firefox at Web 2.0 Security and Privacy 2015