Examine source code of URL Opener

{
  "browser_specific_settings": {
    "gecko": {
      "id": "url-opener@catong"
    }
  },
  "manifest_version": 2,
  "name": "URL Opener",
  "version": "1.0",
  "description": "Open a custom URL.",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "64": "icons/icon-64.png"
  },
  "browser_action": {
    "default_icon": {
      "64": "icons/icon-64.png"
    }
  },
  "permissions": [
    "tabs",
    "storage"
  ],
  "options_ui": {
    "page": "options.html",
    "open_in_tab": false
  }
}