Examine source code of Page Zoom Controller

{
  "manifest_version": 2,
  "name": "Page Zoom Controller",
  "version": "1.0",
  "description": "Easily control the zoom level of any webpage.",
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Zoom Controller"
  },
  "permissions": [
    "tabs",
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{9340d8d6-3f69-4076-85f4-bbc69f481c78}"
    }
  }
}