Examine source code of Closet

{
  "manifest_version": 3,
  "name": "Closet",
  "version": "3.0",
  "description": "Purge distracting tabs instantly.",
  "permissions": [
    "storage",
    "tabs",
    "webNavigation",
    "contextMenus",
    "scripting"
  ],
  "host_permissions": [
    "*://*/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_title": "Open Closet"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "overlay.js"
      ],
      "run_at": "document_start"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "closet@extension.local",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  }
}