Examine source code of Clipboard Master

{
  "manifest_version": 3,
  "name": "Clipboard Extension",
  "version": "1.0",
  "description": "A simple clipboard extension.",
  "browser_specific_settings": {
    "gecko": {
      "id": "clipboardanaselkhaloua@gmail.com"
    }
  },
  "permissions": [
    "activeTab",
    "scripting",
    "clipboardWrite",
    "clipboardRead"
  ],
  "icons": {
    "16": "/ClipMaster16.png",
    "48": "/ClipMaster48.png",
    "128": "/ClipMaster128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "app.js"
      ]
    }
  ],
  "action": {
    "default_popup": "popup.html"
  }
}