Examine source code of JS error notifier

{
  "name": "JS console error notifier",
  "version": "0.1",
  "description": "Show console errors directly in the webpage",
  "icons": {
    "16": "/icons/icon16.png",
    "32": "/icons/icon32.png",
    "48": "/icons/icon48.png",
    "128": "/icons/icon128.png"
  },
  "manifest_version": 2,
  "web_accessible_resources": [
    "/src/console-listener.js",
    "alertify.min.js",
    "fonts/Roboto-Regular.ttf"
  ],
  "permissions": [
    "tabs",
    "webRequest"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://*/*",
        "http://*/*"
      ],
      "run_at": "document_start",
      "css": [
        "/src/alertify.min.css"
      ],
      "js": [
        "contentScript.js",
        "alertify.min.js"
      ]
    }
  ],
  "content_security_policy": "script-src 'self'"
}