Add Mozilla's PDF.js viewer into your pages and posts with a simple shortcode. PDF.js is a javascript library for displaying pdf pages within browsers.
Shortcode Syntax:
[pdfjs-shortcode pdf_width=100% pdf_height=500px pdf_download=true pdf_print=true pdf_openfile=false]
http://www.domain.com/test.pdf[/pdfjs-shortcode]
1)Download from the Wordpress Plugin Repository
2)Upload and expand the archive into your sites wp-content/plugins directory