Examine source code of Online Image Resizer

{
  "manifest_version": 2,
  "name": "Free Online Image Resizer",
  "version": "1.0.0",
  "description": "Resize images with custom dimensions",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icon.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1a41bd85-8116-4516-a293-0a0d94f01671}"
    }
  }
}