mozilla/pdf.js — pull request #5229 by cpeterso (2014-08-22 07:53:09+00:00)
Title: Auto zoom landscape documents (like slide presentations) to fit their height

Landscape documents, like slide presentations, are much easier to read if "Automatic Zoom" fits the slide height so the full slide is visible. Here is an example landscape slide presentation:

https://wiki.mozilla.org/images/5/55/MobileOpportunity.pdf