Examine source code of Tweet That!

{
  "manifest_version": 2,
  "version": "0.3.1resigned1",
  "description": "Tweet the current tab",
  "name": "Tweet That!",
  "homepage_url": "https://github.com/hfiguiere/tweet-that",
  "icons": {
    "16": "data/icon-16.png",
    "32": "data/icon-32.png",
    "64": "data/icon-64.png"
  },
  "permissions": [
    "tabs"
  ],
  "browser_action": {
    "default_icon": "data/icon-32.png",
    "default_title": "Tweet That!",
    "default_popup": "popup/tweetthat.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "applications": {
    "gecko": {
      "id": "jid1-pF9SZq2GsG9cRA@jetpack",
      "strict_min_version": "55.0"
    }
  }
}