Examine source code of Open Random Bookmark

{
  "manifest_version": 2,
  "name": "Open Random Bookmark",
  "version": "1.0.1",
  "description": "Opens a random bookmark from a folder.",
  "icons": {
    "48": "icons/RandomBookmark48.png",
    "96": "icons/RandomBookmark96.png"
  },
  "permissions": [
    "bookmarks",
    "storage",
    "tabs"
  ],
  "browser_action": {
    "default_icon": "icons/RandomBookmark48.png",
    "default_title": "Open Random Bookmark",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{4466649f-6ad9-461d-a094-af8eb8946021}"
    }
  }
}