Examine source code of Captcha Renamer

{
  "manifest_version": 2,
  "name": "Captcha Renamer",
  "version": "1.4",
  "description": "Rename reCAPTCHA v2 text to something silly.",
  "browser_specific_settings": {
    "gecko": {
      "id": "captcha-renamer@example.com"
    }
  },
  "permissions": [
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle",
      "all_frames": true
    }
  ],
  "browser_action": {
    "default_title": "Captcha Renamer",
    "default_popup": "popup.html"
  }
}