Examine source code of Header Override

{
  "manifest_version": 3,
  "name": "Header Override: Modify HTTP Headers & Cookie",
  "description": "Modify request headers, response headers, and cookies with local URL rules and profiles.",
  "version": "1.0.9",
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "permissions": [
    "declarativeNetRequest",
    "storage"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "build/background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "header-override@orest.dev",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "action": {
    "default_title": "Header Override: Modify HTTP Headers & Cookie",
    "default_popup": "build/popup.html",
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png",
      "48": "icons/icon-48.png",
      "128": "icons/icon-128.png"
    }
  }
}