STR: 0. (optional) Start with a fresh Firefox profile. 1. Install Privacy Badger from https://www.eff.org/privacybadger 2. Check the right end of your toolbar for its icon. EXPECTED RESULTS: Privacy Badger icon should show up. ACTUAL RESULTS: No icon (though some blank space does get created to the right of the Firefox Hello icon, and if you click that blank space, you'll see the Privacy Badger menu) ALTERNATE STR: 1. Install Privacy badger in an older version of Firefox. (e.g. current Aurora or Beta). Note that you see its icon. 2. Start up Firefox Nightly using that same profile, and check for the icon. This isn't e10s-related; I get the same results regardless of whether e10s is enabled. Nightly from a month ago gives EXPECTED RESULTS: 39.0a1 (2015-03-16) Nightly from today gives ACTUAL RESULTS: 40.0a1 (2015-04-15) --> regression.
(Note that bug 1006330 tracks a different Privacy Badger issue. Bug 1006330 comment 4 describes something similar to this bug, except that issue was reportedly fixed, and this bug here has become broken in the last month given my results described at the end of comment 0.)
This WFM with Firefox 40.0.3. Can you still reproduce, Dan?
Yup, WORKSFORME. Thanks for noticing this & closing the loop here.
(My testing in comment 3 is using Nightly 44.0a1 (2015-10-08), though it probably doesn't matter)