Examine source code of Siteimprove Browser Extension

{
  "manifest_version": 2,
  "name": "Siteimprove Browser Extension",
  "version": "1.1.1",
  "description": "Measure of the quality and potential impact of a site's digital presence",
  "homepage_url": "https://siteimprove.com",
  "author": "Siteimprove",
  "default_locale": "en",
  "browser_action": {
    "default_title": "Siteimprove"
  },
  "background": {
    "scripts": [
      "./vendor/browser-polyfill.js",
      "./js/background.js"
    ],
    "persistent": true
  },
  "icons": {
    "48": "/img/active.png",
    "128": "/img/active@128x128.png"
  },
  "content_security_policy": "script-src 'self'; object-src 'self'",
  "permissions": [
    "cookies",
    "tabs",
    "activeTab",
    "storage",
    "webRequest",
    "webRequestBlocking",
    "*://*.siteimprove.com/*"
  ]
}