Examine source code of Load Tabs Sequentially

{
  "author": "igorlogius",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_popup": "options.html"
  },
  "icons": {
    "128": "icon.png"
  },
  "manifest_version": 2,
  "name": "Load Tabs Sequentially",
  "options_ui": {
    "page": "options.html"
  },
  "permissions": [
    "tabs",
    "webNavigation",
    "storage"
  ],
  "version": "1.2.8",
  "browser_specific_settings": {
    "gecko": {
      "id": "{61a9f90f-3998-4391-ae2a-f448ffb91097}"
    }
  }
}