Examine source code of Cross Domain - CORS

{
  "manifest_version": 2,
  "version": "0.2.2",
  "name": "Cross Domain - CORS",
  "homepage_url": "https://addons.mozilla.org/en-US/firefox/addon/cross-domain-cors",
  "description": "Cross Domain will help you to deal with cross domain - CORS problem. This is a small tool will helpful for web developer and related domain that face with cross domain issue.",
  "icons": {
    "64": "icons/enable-64.png"
  },
  "background": {
    "scripts": [
      "background-script.js"
    ]
  },
  "browser_action": {
    "default_icon": "icons/enable-64.png",
    "default_title": "Cross Domain - CORS",
    "default_popup": "popup/panel.html"
  },
  "permissions": [
    "activeTab",
    "storage",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "applications": {
    "gecko": {
      "id": "@com.virtualjame.cors",
      "strict_min_version": "57.0"
    }
  }
}