Examine source code of Tab Kraken

{
  "manifest_version": 2,
  "name": "Tab Kraken",
  "version": "0.3.2",
  "description": "Helps sort your tabs",
  "browser_specific_settings": {
    "gecko": {
      "id": "tabkraken@furby.industries"
    }
  },
  "icons": {
    "48": "icons/icon.svg"
  },
  "browser_action": {
    "default_icon": "icons/icon.svg",
    "default_title": "Open Tab Overview"
  },
  "background": {
    "scripts": [
      "external/browser-polyfill.min.js",
      "background.js"
    ]
  },
  "permissions": [
    "tabs",
    "activeTab",
    "management"
  ]
}