" Mozilla recently rolled out Firefox 15, the latest version of the browser in their new rapid-release schedule. With this new release there are quite a few new features, which have been outlined in the above linked post. One interesting feature that bears a little more attention and some explanation is the new built-in PDF reader... "Source: Ghacks.net
Enable the Built-in PDF Reader in Firefox 15
I found that enabling the PDF viewer as described wasn’t enough - I was still opening files in Adobe Reader in a Firefox tab as before. What I had to do, additionally, was to go to Firefox/Options/Applications, type PDF in the search bar, go to the Action drop-down, and select the (newly available) “Preview in Firefox” option. PDFs now open in a nice shiny new Firefox-native viewer. Very neat - all the normal context menu commands work as expected, and the “find” bar finds text within the PDF - really excellent work by the Mozilla people.