Examine source code of Page Notes

{
  "manifest_version": 2,
  "name": "Page Notes",
  "version": "1.3",
  "description": "Save notes for each website page.",
  "applications": {
    "gecko": {
      "id": "{78040c13-b615-4aad-8e00-e19fccd182fc}",
      "strict_min_version": "109.0"
    }
  },
  "permissions": [
    "storage",
    "tabs"
  ],
  "browser_action": {
    "default_title": "Page Notes",
    "default_popup": "popup.html",
    "default_icon": {
      "128": "icon.png"
    }
  }
}