I do confrm the bug
MDL-9721 but I am filling this new bug in order to increase the priority.
Add a PDF document to a course as "Link to a file or web site" with
-> "Window" = same window
-> "Keep page navigation visible on the same page" checkbox selected.
If the user doesn't have the plug-in to open the PDF inside the internet browser, the PDF page appear empty and on the top of the content free page is written: "To open this document, click on this link:" BUT THE LINK IS NOT PRESENT
This bug is new. It was perfectly working few weeks ago.