Examine source code of CSP Tester

{
  "manifest_version": 2,
  "name": "CSP Tester",
  "description": "This extension helps web masters to test web application behaviour with Content Security Policy version 2.0 implemented.",
  "version": "2.2resigned1",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "browser_action": {
    "default_icon": "icon16.png",
    "default_popup": "popup.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "homepage_url": "https://oxdef.info/csp-tester",
  "applications": {
    "gecko": {
      "id": "csp-tester@oxdef.info",
      "strict_min_version": "45.0"
    }
  }
}