Examine source code of Margin Notes

{
  "manifest_version": 2,
  "name": "Margin Notes",
  "version": "1.0",
  "description": "Write notes directly in the page margins.",
  "permissions": [
    "activeTab",
    "storage"
  ],
  "browser_action": {
    "default_title": "Add Margin Notes",
    "default_popup": "popup.html"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{779ef8d5-8b7b-4be6-b708-bbebde27c1f0}"
    }
  }
}