client/site_tests/policy_ExtensionPolicy/policy_test_extension/manifest.json

{
  "manifest_version": 2,

  "name": "Policy Extension",
  "description": "Dummy extension for testing extension policies",
  "version": "1.0",

  "background": {
      "scripts": ["background.js"],
      "persistent": false
  },

  "storage": {
      "managed_schema": "schema.json"
  },

  "permissions": [
      "storage"
  ]
}