Gnome Shell Integration in Chrome not working
Chrome and Chromium dropped support for the NPAPI plugins (Netscape Plugin Application Programming Interface) in favor of PPAPI (Pepper Plugin Application Programming Interface) so all plugins that use NPAPI (like GNOME Extension plugin) are just not supported.
The only alternative is using another browser that allows them (like Firefox) or asking the developers to move to PPAPI (unlikely).
NOTE: This is the blog post from the Chromium blog mentioning this, titled: Saying Goodbye to Our Old Friend NPAPI.
You want to install the "chrome-gnome-shell" (and probably also the "GNOME Shell Integration" Chrome Extension)
You can find instructions to install chrome-gnome-shell for your distro here on the GNOME wiki.
Essentially, install for your distro:
- Ubuntu - available from ppa:ne0sight/chrome-gnome-shell.
- Fedora - available from region51/chrome-gnome-shell copr.
- Gentoo - Ebuild is available in the main tree.
- Arch - available in the AUR: chrome-gnome-shell.
- Other
And then add the Chrome Extension.