@nprofile1q... I don't really understand the point of the web based pdf reader, since Firefox would use a pdf.js-like reader anyway (and it is way faster to load than ACM's), and Chrome has its built-in PDF viewer too. It might've made sense before 2013 when Firefox didn't have a built-in PDF viewer. And if they do want to embed a web based reader why not embed pdf.js which is a lot faster?