Examine source code of Visit Reminder

{
  "manifest_version": 2,
  "name": "Visit Reminder",
  "version": "1.0.2",
  "description": "Local visit reminder grouped by domain with first and last visit times.",
  "permissions": [
    "history"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Visit Reminder"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "visitreminder@speedex",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}