Examine source code of Adjust Tab Selection

{
  "description": "This extension allow you select the parent after close the child tabs",
  "manifest_version": 2,
  "name": "Adjust Tab Selection",
  "version": "0.0.4resigned1",
  "homepage_url": "https://github.com/harytfw/GlitterDrag",
  "author": "harytfw",
  "permissions": [
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "applications": {
    "gecko": {
      "id": "adjusttabselection@harytfw",
      "strict_min_version": "52.0"
    }
  }
}