Examine source code of tabPreLoader

{
  "applications": {
    "gecko": {
      "strict_min_version": "57.0a1",
      "id": "jid1-VEYBpA8EfyS7Kg@jetpack"
    }
  },
  "manifest_version": 2,
  "name": "__MSG_extensionName__",
  "version": "0.8.3",
  "homepage_url": "https://github.com/jmozmoz/tabpreloader",
  "description": "__MSG_extensionDescription__",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "page": "options/options.html",
    "browser_style": true
  },
  "permissions": [
    "tabs",
    "storage",
    "alarms"
  ],
  "icons": {
    "48": "icons/tabPreLoader-48.png"
  },
  "default_locale": "en"
}