Examine source code of Silent Info Cube

{
  "manifest_version": 2,
  "name": "Silent Info Cube",
  "version": "1.0.0",
  "description": "A static information cube displayed in a popup. Fully offline and requires no permissions.",
  "permissions": [],
  "browser_action": {
    "default_title": "Silent Info Cube",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "silent-info-cube@example.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "data_collection_permissions": [],
  "data_collection": {
    "collects_data": false
  }
}