Created attachment 218487 [details]
1. with a few extensions installed
3. developer mode
4. click Update
– the 'Updating…' status appears, does not disappear.
Worked around by manually identifying then removing a number of extensions that are no longer in Google's store.
I guess I'll find an upstream bug for this …
Chromium bug 1121468 - Extensions page: "Updating…" in Developer Mode stays forever