Examine source code of sortable

{
  "description": "Adds a page action to make tables sortable.",
  "manifest_version": 2,
  "name": "sortable",
  "version": "1.3",
  "homepage_url": "https://github.com/danielheath/sortable",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "page_action": {
    "default_icon": "icons/off.svg",
    "browser_style": true
  },
  "permissions": [
    "activeTab",
    "tabs"
  ]
}