Examine source code of Keep Tab Active

{
  "manifest_version": 3,
  "name": "Keep Tab Active",
  "version": "0.1.0",
  "description": "Makes selected tabs appear visible and focused to the page.",
  "permissions": [
    "scripting",
    "storage"
  ],
  "icons": {
    "16": "icons/kta-16.png",
    "32": "icons/kta-32.png",
    "48": "icons/kta-48.png",
    "128": "icons/kta-128.png"
  },
  "action": {
    "default_title": "Keep Tab Active: off",
    "default_icon": {
      "16": "icons/kta-16.png",
      "32": "icons/kta-32.png"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "service_worker": "background.js"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "@keep-tab-active.patri",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "page.js"
      ],
      "run_at": "document_start",
      "all_frames": true,
      "world": "MAIN"
    },
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start",
      "all_frames": true
    }
  ]
}