Examine source code of Proxy Selector

{
  "manifest_version": 2,
  "name": "Proxy Selector",
  "version": "1.0",
  "description": "Set up different proxy profiles by nickname.",
  "permissions": [
    "proxy",
    "storage"
  ],
  "applications": {
    "gecko": {
      "id": "proxyselector@example.com",
      "strict_min_version": "91.1.0"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Proxy Selector"
  }
}