Examine source code of HTTP Error Detector

{
  "manifest_version": 2,
  "name": "HTTP Error Detector",
  "version": "1.1",
  "description": "Detect and display HTTP status codes on websites.",
  "icons": {
    "64": "icons/logo_64.png"
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "tabs",
    "notifications",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": "icons/logo_64.png",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{da23d15b-0d6c-4e2b-b733-dc54791b92a1}"
    }
  }
}