Examine source code of Alx Knife

{
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "alxknife@alx.com",
      "strict_min_version": "92.0"
    },
    "gecko_android": {
      "strict_min_version": "92.0"
    }
  },
  "name": "Alx Knife",
  "version": "1.0.10",
  "author": "Alx",
  "icons": {
    "96": "icon.png"
  },
  "description": "HTTP Header Knife inserts HTTP headers and script on a per host basis.",
  "homepage_url": "https://interno.altervista.org/",
  "background": {
    "scripts": [
      "HttpHeaderKnife.js"
    ]
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": false
  },
  "permissions": [
    "storage",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>",
    "activeTab",
    "scripting",
    "tabs",
    "clipboardRead",
    "clipboardWrite",
    "cookies"
  ]
}