Examine source code of Dongrami

{
  "description": "Dongrami(동그라미)는 트위터의 서클기능을 임의로 활성화합니다.",
  "manifest_version": 2,
  "name": "Dongrami",
  "author": "Gaeulbyul <aeiou256@gmail.com>",
  "version": "0.0.0.1",
  "homepage_url": "https://github.com/gaeulbyul/Dongrami",
  "icons": {
    "48": "icons/icon-48.png",
    "64": "icons/icon-64.png",
    "128": "icons/icon-128.png"
  },
  "permissions": [
    "https://twitter.com/*",
    "https://mobile.twitter.com/*"
  ],
  "web_accessible_resources": [
    "dongrami.js"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://twitter.com/*",
        "https://mobile.twitter.com/*"
      ],
      "exclude_matches": [
        "https://*.twitter.com/about",
        "https://*.twitter.com/download",
        "https://*.twitter.com/intent/*",
        "https://*.twitter.com/privacy",
        "https://*.twitter.com/tos",
        "https://*.twitter.com/*/privacy",
        "https://*.twitter.com/*/tos"
      ],
      "run_at": "document_idle",
      "js": [
        "loader.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d5cabc9f-1809-4bdd-b49d-cdbb39942ac8}"
    }
  }
}