Examine source code of Domain Switcher azaw

{
  "manifest_version": 2,
  "name": "Domain Switcher",
  "version": "1.0",
  "description": "Switch between configured domains.",
  "homepage_url": "https://github.com/AlbertZawadzki/firefox-domain-switcher",
  "permissions": [
    "tabs",
    "storage"
  ],
  "browser_action": {
    "default_icon": "icon-dark.png",
    "default_title": "Domain Switcher",
    "default_popup": "popup.html"
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{437f099d-aecc-487e-b6d5-f6eeebd45d1b}"
    }
  }
}