The PDF Viewer doesn’t have a toolbar button, but you should find it listed on the Firefox add-on page. Check out this page and click on the + Add to Firefox option to install it. The Firefox PDF Viewer add-on gives you an effective PDF document viewer for the browser. However, you can still open PDF documents in Firefox.
The Firefox browser does not include any built-in options with which to open PDF documents. This article covers opening PDF documents with Google Chrome. You can open PDF (Portable Document Format) documents with both PDF software and browsers.
