Examine source code of LeetCode Manual Checker

{
  "manifest_version": 3,
  "name": "LeetCode Manual Checker",
  "version": "1.0",
  "description": "Adds a manual checkbox before each LeetCode problem. Persists marks across restarts.",
  "permissions": [
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://leetcode.com/*"
      ],
      "js": [
        "content_script.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "icons": {
    "48": "icon48.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "r1jahagirdar@gmail.com",
      "strict_min_version": "109.0"
    }
  }
}