Examine source code of Proxy Toggle

{
  "manifest_version": 2,
  "author": "ipuig",
  "version": "1.1",
  "name": "Proxy Toggle",
  "description": "Toggle custom proxy setting by clicking the extension's icon",
  "icons": {
    "48": "assets/icons/base.png",
    "96": "assets/icons/base.png"
  },
  "browser_action": {
    "default_popup": "popup/popup.html",
    "default_icon": "assets/icons/base.png"
  },
  "permissions": [
    "browserSettings",
    "proxy"
  ],
  "browser_specific_settings": {
    "gecko": {
      "strict_min_version": "91.1.0",
      "id": "{671e9374-449c-4488-a40c-31e1ef38683b}"
    }
  }
}