Examine source code of HackBar

{
  "description": "A HackBar for google chrome/firefox browser. Small tool for pentesting websercurity.",
  "manifest_version": 2,
  "name": "HackBar",
  "version": "2.3.1",
  "author": "Khoiasd",
  "homepage_url": "https://hackbar.herokuapp.com",
  "icons": {
    "48": "icons/icon.png"
  },
  "permissions": [
    "tabs",
    "activeTab",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>",
    "storage"
  ],
  "devtools_page": "theme/hackbar.html",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e77bc9b7-5db1-4f7e-af96-eccd2a6eb70f}"
    }
  }
}