Examine source code of Screenshots Extension

{
  "name": "Screenshot Extension",
  "version": "1.0",
  "description": "Building a screenshot-taking extension",
  "manifest_version": 2,
  "permissions": [
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{adf64b83-337d-4696-822c-9da5623a7040}"
    }
  }
}