Examine source code of Save Media As Category

{
  "manifest_version": 2,
  "name": "Save Image As Category",
  "version": "1.81",
  "description": "Right-click an image to save it to a specific category.",
  "permissions": [
    "contextMenus",
    "downloads",
    "activeTab",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "48": "icons/icon.png"
  },
  "browser_action": {
    "default_icon": "icons/icon.png",
    "default_popup": "popup/popup.html"
  },
  "applications": {
    "gecko": {
      "id": "{4822ebf7-f636-433f-ac97-e7961e44125c}"
    }
  }
}