Examine source code of Codeforces Streak

{
  "manifest_version": 3,
  "name": "Codeforces Streak",
  "version": "1.0.0",
  "description": "Shows Codeforces streak beside username",
  "browser_specific_settings": {
    "gecko": {
      "id": "cf-streak@yourhandle",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://codeforces.com/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ]
}