Examine source code of Permission Revoker

{
  "manifest_version": 2,
  "name": "Permission Revoker",
  "version": "2.4.9",
  "description": "Auto-revokes unused permissions.",
  "browser_specific_settings": {
    "gecko": {
      "id": "{253b8803-ff49-499f-b859-a83786286ddc}",
      "strict_min_version": "101.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>",
    "cookies",
    "storage"
  ],
  "browser_action": {
    "default_icon": {
      "16": "icons/icon-16.png",
      "48": "icons/icon-48.png",
      "64": "icons/icon-64.png",
      "128": "icons/icon-128.png"
    },
    "default_title": "Permission Revoker",
    "default_popup": "popup/popup.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "16": "icons/icon-16.png",
    "48": "icons/icon-48.png",
    "64": "icons/icon-64.png",
    "128": "icons/icon-128.png"
  }
}