The current text is:
[Provider Name] integration with Firefox has been activated.
Rather than using the passive voice, we could use the active voice:
You've turned on Firefox's [Provider Name] support.
You've turned on [Provider Name] for Firefox.
Created attachment 655174 [details] [diff] [review]
Can you double check that the menu item accesskey doesn't conflict? Not much hardcoded text to go on here.
Comment on attachment 655174 [details] [diff] [review]
I double checked the access key and it looks good to me.