Examine source code of Tab Sort by Domain

{
  "manifest_version": 2,
  "name": "Tab Sort by Domain",
  "version": "1.0.0",
  "description": "Sort all tabs in the current window alphabetically by domain.",
  "icons": {
    "512": "filter.png"
  },
  "permissions": [
    "tabs"
  ],
  "browser_action": {
    "default_icon": {
      "512": "filter.png"
    },
    "default_title": "Sort tabs by domain"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "tab-sort@ian.camb.io",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  }
}