Mozilla Foundation has decided to update their add-on and extension infrastructure, making Firefox more capable and user-friendly. The move will help Firefox in various ways like: Integration of new technologies like Electrolysis and Servo protections from Adware and Spyware, shortening the time it takes to review add-ons. A mandatory extension signing is coming to Firefox, which is an escape from malicious developers in the world taking advantage of others. The extension’s code will run in a different process from content, unlike the current scenario, where a single operating system process contains all the information.
Source: https://thehackernews.com/2015/08/mozilla-firefox-web-extensions.html

