Examine source code of Close Tabs by URL

{
  "manifest_version": 2,
  "name": "Close Tabs by URL",
  "version": "0.1",
  "description": "Closes all tabs of the website based on the URL of the current tab.",
  "homepage_url": "https://github.com/ndxf/Close-Tabs-by-URL",
  "icons": {
    "16": "icons/icon-16.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "permissions": [
    "tabs",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/icon-16.png",
      "48": "icons/icon-48.png",
      "128": "icons/icon-128.png"
    },
    "default_title": "Close Tabs by URL",
    "default_popup": "popup/popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1af219a9-bc64-4f99-a890-7ec41720b881}"
    }
  }
}