Examine source code of Save Ultimate-Guitar Tab

{
  "description": "Download ultimate-guitar.com Official GPX Tabs [Pro Account Only]",
  "manifest_version": 2,
  "name": "Save Ultimate-Guitar Official Tab",
  "version": "1.2",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "storage",
    "unlimitedStorage",
    "downloads",
    "tabs",
    "https://tabs.ultimate-guitar.com/tab/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "strict_min_version": "57.0a1",
      "id": "ug-pro-gpx-save-1.1@tsundokul"
    }
  },
  "developer": {
    "name": "Timofte Daniel",
    "url": "https://twitter.com/tim17d"
  },
  "browser_action": {
    "browser_style": true,
    "default_icon": {
      "48": "pick-active.svg"
    }
  }
}