Examine source code of SmartSwitch

{
  "name": "SmartSwitch",
  "description": "Transfer your YouTube channel subscriptions to another account with just a few clicks.",
  "version": "1.6",
  "manifest_version": 2,
  "default_locale": "en",
  "icons": {
    "16": "src/assets/icons/icon_16.png",
    "32": "src/assets/icons/icon_32.png",
    "48": "src/assets/icons/icon_48.png",
    "128": "src/assets/icons/icon_128.png"
  },
  "permissions": [
    "storage",
    "clipboardWrite",
    "alarms",
    "tabs",
    "https://www.youtube.com/*",
    "https://youtube.com/*"
  ],
  "background": {
    "scripts": [
      "service-worker-loader.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "src/popup/popup.html",
    "default_icon": {
      "16": "src/assets/icons/icon_16.png",
      "32": "src/assets/icons/icon_32.png",
      "48": "src/assets/icons/icon_48.png",
      "128": "src/assets/icons/icon_128.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{69291c5b-bf91-4068-808d-b1f84f64e5c9}"
    }
  }
}