Examine source code of Follow Hound

{
  "manifest_version": 2,
  "name": "Follow Hound",
  "description": "Quickly and easily see which Twitter users follow you back.",
  "version": "1.2resigned1",
  "short_name": "Quickly and easily see which Twitter users follow you back.",
  "homepage_url": "http://tech-in-check.blogspot.com/",
  "icons": {
    "48": "fh_icon48.png",
    "96": "fh_icon96.png"
  },
  "browser_action": {
    "default_icon": {
      "48": "fh_icon48.png",
      "96": "fh_icon96.png"
    },
    "default_title": "Follow Hound"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "permissions": [
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{46f78996-c515-49fb-9dbc-01b52f912d4f}"
    }
  }
}