Examine source code of Recent Tab Switcher

{
  "manifest_version": 3,
  "name": "Recent Tab Switcher",
  "version": "1.1.0",
  "description": "A cross-browser extension",
  "browser_specific_settings": {
    "gecko": {
      "id": "recent-tab-switcher@mvargas",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "16": "icons/icon-16.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon-16.png",
      "48": "icons/icon-48.png",
      "128": "icons/icon-128.png"
    }
  },
  "background": {
    "service_worker": "background.js",
    "scripts": [
      "background.js"
    ],
    "type": "module"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "lib/browser-polyfill.min.js",
        "content.js"
      ]
    }
  ],
  "permissions": [
    "history",
    "storage",
    "tabs"
  ],
  "commands": {
    "_execute_action": {
      "suggested_key": {
        "default": "Ctrl+E",
        "mac": "MacCtrl+E"
      },
      "description": "Open the popup"
    }
  }
}