Examine source code of HTML Ref

{
  "manifest_version": 2,
  "name": "HTML Ref",
  "version": "1.0",
  "description": "A sidebar with an HTML element reference",
  "permissions": [
    "activeTab"
  ],
  "sidebar_action": {
    "default_title": "HTML Ref",
    "default_panel": "sidebar.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "html_ref@example.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  }
}