That was my usual extension management method for chrome, but sadly each time I tried that on firefox, it didn't fly (IIRC, you _can_ load extension from your local FS, but they only lives for the time of the session).

By the way, if someone from firefox team is reading this : I would _really_ love to be able to just load directories from my FS as extensions rather than having to trust someone on the internet that it does what it says it does. I love building extensions myself, but I just don't install extensions from the web anymore because I don't know what's in there (note that referring to a github repos is not enough : I have no guarantee the content of the extension is the same).

Or you can just setup google container manually, it's not so much work in Firefox.