Examine source code of ZoomPage

{
  "manifest_version": 2,
  "name": "ZoomPage",
  "description": "Zoom Extension, slider to increase page element size",
  "version": "1.0",
  "browser_action": {
    "default_popup": "./popup.html",
    "default_title": "ZoomPage"
  },
  "icons": {
    "16": "./zoom16.png",
    "48": "./zoom48.png",
    "128": "./zoom128.png",
    "256": "./zoom256.png"
  },
  "permissions": [
    "tabs",
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{7ca6aae2-7307-4a7a-8bc0-9f632863f8da}"
    }
  }
}