Examine source code of NicCage

{
  "manifest_version": 2,
  "name": "NicCage",
  "version": "1.3",
  "description": "This addon replaces images with pictures of Nicholas Cage. What isn't there to love?",
  "applications": {
    "gecko": {
      "id": "jid1-R4K9NQmQx8Ciug@jetpack"
    }
  },
  "icons": {
    "32": "icon-32.png",
    "48": "icon-48.png",
    "64": "icon-64.png",
    "128": "icon-128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "cageify.js"
      ]
    }
  ],
  "permissions": [
    "storage"
  ],
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  },
  "homepage_url": "http://github.com/pvrs12/NicCageAddon"
}