Works Perfectly on Latest WordPress

The pdf.js plugin works perfectly in WordPess 4.9.8. The only thing I had to do in order to customize it was to edit the file pdfjs-viewer.php and on line 64 add a class and a target.

$fullscreen_link = '<a href="'.$final_url.'" class="pdf-full-link" target="_blank">View Fullscreen</a><br>';