Full list feature changes in this commit:
- Support for iframes
- Switched to content-type (MIME) detection instead of hard-coding a
case-sensitive check for the .PDF extension
- The PDF's original URL is visible in the omnibox
- Support for incognito mode
Note: PDF viewer is disabled for the file:// + incognito
combination, because it's currently impossible to get the combination
to work.
See https://github.com/mozilla/pdf.js/pull/3017#issuecomment-15693432
