Examine source code of PrivateSearch

{
  "manifest_version": 2,
  "name": "Private Search",
  "version": "1.2resigned1",
  "permissions": [
    "contextMenus",
    "search"
  ],
  "description": "Adds a context menu option to search the selected text in a new Private Window using your default search engine.",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "background": {
    "scripts": [
      "private_search.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{fabd4689-5741-4c53-81a2-e53315c80b98}"
    }
  }
}