Examine source code of Clear URL Tracker it

{
  "manifest_version": 2,
  "name": "Clear URL Tracker",
  "version": "1.0",
  "description": "Remove tracking parameters from URLs.",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5f6d4cbd-5c48-494d-b65a-315e48b9dc7a}"
    }
  }
}