This extension does nothing. (It once enabled 280-character tweets on Twitter and TweetDeck, but Twitter has now blocked that.)
Update Oct 5: This extension no longer works. Twitter and TweetDeck are now both validating tweet length at the API. ⚰️
Update Sep 28: The party is over at twitter.com, which now appears to be validating tweet length at the server, so this extension no longer enables 280-character tweets there. But it still works at tweetdeck.twitter.com! 🎉
Twitter released 280-character tweeting, but only to a small group of people during a trial period. This Chrome extension once added the ability for everyone to tweet in 280 characters on Twitter and TweetDeck.
The source code is available at https://github.com/quinncomendant/280Characters and pull requests are invited.