Examine source code of What Font OLI

{
  "description": "View computed font attributes.",
  "manifest_version": 2,
  "name": "What Font OLI",
  "version": "1.3resigned1",
  "homepage_url": "https://addons.mozilla.org/it/firefox/user/kushan4157/",
  "icons": {
    "48": "icons/icon-48.png",
    "64": "icons/icon-64.png",
    "128": "icons/icon-128.png"
  },
  "background": {
    "scripts": [
      "config.js"
    ]
  },
  "permissions": [
    "activeTab",
    "menus"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{0b7020de-67b2-49ee-8f67-0e7c2c1c7c39}"
    }
  }
}