Examine source code of Save Image As

{
  "manifest_version": 3,
  "name": "Save image as",
  "description": "Save any image as PDF, PNG, JPG or WebP.",
  "version": "1.0",
  "browser_specific_settings": {
    "gecko": {
      "id": "save-image-as@local.addon",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  },
  "permissions": [
    "downloads",
    "contextMenus",
    "storage",
    "scripting"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "i18n.js",
      "background.js"
    ]
  },
  "action": {
    "default_title": "Save image as",
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/16.png",
      "32": "icons/32.png",
      "48": "icons/48.png"
    }
  },
  "icons": {
    "16": "icons/16.png",
    "32": "icons/32.png",
    "48": "icons/48.png",
    "96": "icons/96.png",
    "128": "icons/128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle",
      "all_frames": true
    }
  ]
}