Examine source code of 4mat

{
  "name": "4mat",
  "version": "1.4",
  "description": "A Chrome extension for quick conversions of MAC addresses",
  "manifest_version": 2,
  "icons": {
    "16": "assets/images/icon16.png",
    "48": "assets/images/icon48.png",
    "128": "assets/images/icon128.png"
  },
  "browser_action": {
    "default_icon": "assets/images/icon16.png",
    "default_popup": "assets/html/macr.html"
  },
  "background": {
    "scripts": [
      "assets/js/macr.js"
    ],
    "persistent": false
  },
  "permissions": [
    "tabs",
    "clipboardRead"
  ]
}