This is an extension to Gnome Shell (git repo here) that makes switching between Gnome’s proxy profiles simpler. Gnome’s proxy profiles (“Automatic”, “Manual” and “None”) determine the system-wide proxy settings used by (among other things) Google Chrome.
The extension is translated into lots of different languages. I was able to do this because the phrases used in the extension also appear in the Network Settings program gnome-control-center, and have therefore been translated already by others.