Examine source code of Nested tab numbering

{
  "manifest_version": 2,
  "name": "Nested tab numbering",
  "version": "1.1.0",
  "description": "Displays nested/flat tab counts for Tree Style Tab",
  "homepage_url": "https://github.com/ryanyrzh/Nested_tab_numbering",
  "permissions": [
    "tabs",
    "storage",
    "management",
    "https://addons.mozilla.org/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Nested tab numbering",
    "default_popup": "options.html"
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "nested-tab-numbering@ryanyrzh.com",
      "strict_min_version": "78.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}