mozilla/pdf.js — pull request #1969 by ariofrio (2012-08-09 07:46:20+00:00)
Title: Keep URL in Chrome extension, fixes #1511

I achieve this by replacing the embed (for Chrome's native PDF viewer) with an iframe. It is not clear to me yet how to synchronize the title (a look at the PDF.js API would probably do the trick).

An alternative approach would be to replace the contents of the page. This would allow extensions like Vimium to work.