Examine source code of Sync storage test

{
  "manifest_version": 2,
  "applications": {
    "gecko": {
      "id": "sync-storage-test@ne0sight",
      "strict_min_version": "52.0"
    }
  },
  "name": "Sync storage test",
  "version": "4resigned1",
  "author": "Yuri Konotopov <ykonotopov@gnome.org>",
  "background": {
    "scripts": [
      "extension.js"
    ],
    "persistent": false
  },
  "options_ui": {
    "page": "options.html",
    "chrome_style": true
  },
  "permissions": [
    "storage"
  ]
}