Examine source code of yt-time-left

{
  "name": "yt-time-left",
  "description": "__MSG_description__",
  "version": "0.2.3",
  "version_name": "Init",
  "manifest_version": 2,
  "author": "Nawot",
  "homepage_url": "https://github.com/Nawot/yt-time-left",
  "default_locale": "en",
  "icons": {
    "8": "icons/icon.svg",
    "16": "icons/icon.svg",
    "24": "icons/icon.svg",
    "48": "icons/icon.svg",
    "64": "icons/icon.svg",
    "128": "icons/icon.svg",
    "256": "icons/icon.svg",
    "512": "icons/icon.svg",
    "1024": "icons/icon.svg"
  },
  "applications": {
    "gecko": {
      "id": "Nawot001@gmail.com",
      "strict_min_version": "68.0"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.youtube.com/watch*"
      ],
      "js": [
        "yt-time-left.js"
      ],
      "run_at": "document_end"
    }
  ],
  "permissions": [
    "storage",
    "https://sponsor.ajay.app/api/*",
    "webRequest"
  ],
  "options_ui": {
    "page": "options/options.html"
  }
}