Examine source code of Visually-Revealed

{
  "manifest_version": 2,
  "name": "Visually-Revealed",
  "version": "1.0",
  "description": "Visually reveals all elements with class 'sr-only' or 'visually-hidden' for quick testing/debugging.",
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "browser_action": {
    "default_icon": "icons/eye-off.svg"
  },
  "background": {
    "scripts": [
      "visually-revealed.js"
    ]
  }
}