Examine source code of Gmail Same Tab Switcher

{
  "manifest_version": 2,
  "name": "Gmail Same Tab Switcher",
  "version": "1.0",
  "description": "Переключение аккаунтов Gmail в той же вкладке",
  "permissions": [
    "tabs",
    "webRequest",
    "webRequestBlocking",
    "*://mail.google.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "gmail-same-tab-switcher@extension",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  }
}