Examine source code of Return Old Twitter Logo

{
  "manifest_version": 2,
  "name": "Return Old Twitter Logo",
  "version": "1.0.1",
  "description": "Replaces the new X logo with the blue bird icon",
  "icons": {},
  "content_scripts": [
    {
      "matches": [
        "*://*.twitter.com/*"
      ],
      "js": [
        "returntwt.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d4645440-9414-4f0d-b000-2cfb124abcfc}"
    }
  }
}