Examine source code of IJK

{
  "description": "IRIAM で使用した JASRAC の楽曲申請を KANTAN にするやつです",
  "manifest_version": 2,
  "name": "IJK",
  "version": "1.0.7",
  "icons": {
    "96": "icons/ijk-96.png"
  },
  "browser_action": {
    "default_icon": "icons/ijk-32.png",
    "default_title": "IJK",
    "default_popup": "popup/popup.html"
  },
  "permissions": [
    "storage",
    "tabs"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://www2.jasrac.or.jp/eJwid/*"
      ],
      "js": [
        "js/browser-polyfill.js",
        "contents/ijk.js"
      ],
      "css": [
        "contents/ijk.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{a798d6a0-bbc2-4dd9-9009-1e57bb62efb9}"
    }
  }
}