Examine source code of Bookmark id

{
  "manifest_version": 2,
  "name": "Bookmark id",
  "version": "1.0",
  "description": "Get a bookmark's id given it's title.",
  "icons": {
    "48": "img/icon48.png"
  },
  "browser_action": {
    "default_icon": "img/icon32.png",
    "default_title": "Bookmark id",
    "default_popup": "index.html"
  },
  "permissions": [
    "<all_urls>",
    "bookmarks"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{a57e0fcc-7824-4ddf-923c-b12190d6f793}"
    }
  }
}