Examine source code of Linkdown

{
  "manifest_version": 2,
  "name": "Linkdown",
  "version": "1.0",
  "description": "A simple button to copy links for markdown",
  "icons": {
    "48": "icons/linkdown48.png",
    "96": "icons/linkdown96.png"
  },
  "background": {
    "scripts": [
      "app.js"
    ]
  },
  "permissions": [
    "tabs",
    "clipboardWrite"
  ],
  "browser_action": {
    "default_icon": "icons/linkdown32.png",
    "default_title": "Linkdown"
  }
}