Examine source code of StorageTester

{
  "manifest_version": 2,
  "name": "StorageTester",
  "description": "Testing web extension storage behavior",
  "version": "0.2resigned1",
  "default_locale": "en",
  "applications": {
    "gecko": {
      "strict_min_version": "52.0",
      "id": "{ec104920-3e36-4df7-8141-f94e9a6bcd5e}"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "menus",
    "storage"
  ],
  "icons": {
    "16": "icons/page-16.png",
    "32": "icons/page-32.png",
    "48": "icons/page-48.png"
  },
  "sidebar_action": {
    "default_icon": "icons/page-32.png",
    "default_title": "Storage Tester",
    "default_panel": "sidebar/sidebar.html"
  }
}