Examine source code of Toggle Page Fonts

{
  "manifest_version": 2,
  "name": "Toggle Page Fonts",
  "version": "1.0",
  "description": "Toggle a page's fonts On or Off",
  "browser_action": {
    "default_icon": {
      "48": "Icons/off.svg",
      "96": "Icons/off.svg"
    }
  },
  "background": {
    "scripts": [
      "background-script.js"
    ]
  },
  "icons": {
    "48": "Icons/on.svg",
    "96": "Icons/on.svg"
  },
  "permissions": [
    "browserSettings"
  ]
}