Examine source code of Yakitorikun

{
  "manifest_version": 2,
  "name": "Yakitorikun",
  "version": "1.1",
  "description": "Deny access to Twitter.",
  "icons": {
    "48": "image/icon-48.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.twitter.com/*"
      ],
      "js": [
        "access.js"
      ]
    }
  ],
  "browser_action": {
    "default_icon": {
      "19": "image/icon-19.png",
      "38": "image/icon-38.png"
    }
  }
}