Examine source code of Ratero

{
  "description": "Adds an option to steal tweets to twitter",
  "manifest_version": 2,
  "name": "Ratero",
  "version": "1.0",
  "homepage_url": "https://github.com/levhita/ratero",
  "icons": {
    "48": "icons/ratero-48.png",
    "96": "icons/ratero-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://twitter.com/*"
      ],
      "js": [
        "ratero.js"
      ]
    }
  ]
}