Examine source code of Game Time Tracker

{
  "manifest_version": 2,
  "name": "Game Time Tracker",
  "version": "1.0",
  "description": "Track how much time you spend on game-related websites.",
  "permissions": [
    "tabs",
    "storage",
    "https://store.steampowered.com/*",
    "https://www.epicgames.com/*",
    "https://www.gog.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html",
    "default_title": "Game Time Tracker"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{cf097f41-684d-48f3-8e24-e7aaff7ab387}"
    }
  }
}