Examine source code of Clipper

{
  "manifest_version": 3,
  "name": "Clipper",
  "version": "1.3",
  "description": "Bypasses clipboard restrictions on webpages",
  "icons": {
    "16": "clipper-16.png",
    "48": "clipper-48.png"
  },
  "homepage_url": "https://github.com/GNUGradyn/Clipper",
  "action": {
    "default_icon": "clipper-16.png",
    "default_title": "Clipper",
    "default_popup": "popup/popup.html"
  },
  "permissions": [
    "tabs",
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "browser-polyfill.min.js",
        "inject.js"
      ],
      "run_at": "document_start",
      "all_frames": true
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "clipper@gradyn.com"
    }
  }
}