Examine source code of LookUp

{
  "manifest_version": 2,
  "name": "LookUp",
  "version": "1.0.2resigned1",
  "default_locale": "en",
  "description": "__MSG_AddOnDescription__",
  "applications": {
    "gecko": {
      "id": "lookup@patonnier.net",
      "strict_min_version": "47.0"
    }
  },
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "permissions": [
    "<all_urls>",
    "tabs",
    "storage",
    "downloads"
  ],
  "background": {
    "scripts": [
      "lib/browser-polyfill.js",
      "lib/storage.js",
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "lib/browser-polyfill.js",
        "inspector.js"
      ]
    }
  ],
  "options_ui": {
    "page": "ui/settings.html"
  },
  "browser_action": {
    "default_icon": "icons/icon-48.png",
    "default_title": "LookUp",
    "default_popup": "ui/panel.html"
  }
}