Examine source code of local-DNS

{
  "name": "local-DNS",
  "description": "resolve short onion readable links to long onion links. For example: duckduckgo.on -> duckduckgogg42xjoc72x3sjasowoarfbgcmvfimaftt6twagswzczad.onion",
  "homepage_url": "https://ext.play-it.net/local-DNS",
  "version": "0.2",
  "manifest_version": 2,
  "icons": {
    "48": "icons/default.svg#bg",
    "96": "icons/default.svg#bg"
  },
  "permissions": [
    "storage",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "DNS.js",
      "background.js"
    ]
  },
  "page_action": {
    "default_icon": {
      "48": "icons/default.svg",
      "92": "icons/default.svg"
    },
    "default_title": "Add a DNS entry",
    "default_popup": "popup/index.html",
    "show_matches": [
      "*://*.onion/*"
    ]
  },
  "options_ui": {
    "page": "options/index.html",
    "open_in_tab": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "local-DNS@play-it.net"
    }
  }
}