Examine source code of VK notifications

{
  "manifest_version": 3,
  "name": "VK notifications",
  "version": "1",
  "browser_specific_settings": {
    "gecko": {
      "id": "{613175bf-9bdb-42c3-b41e-fc107e482788}",
      "strict_min_version": "42.0"
    }
  },
  "description": "",
  "content_scripts": [
    {
      "matches": [
        "*://*.vk.com/*"
      ],
      "js": [
        "script.js"
      ]
    }
  ]
}