Examine source code of Pencil Window

{
  "manifest_version": 3,
  "name": "Pencil Window",
  "version": "1.0.0",
  "description": "Draw on any page. Your strokes follow scroll and stay per URL. Open a notes dashboard to jump back to any saved drawing.",
  "icons": {
    "16": "icon 300x300/pencil-cursor 300x300.png",
    "48": "icon 300x300/pencil-cursor 300x300.png",
    "128": "icon 300x300/pencil-cursor 300x300.png"
  },
  "action": {
    "default_title": "Pencil Window",
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icon 300x300/pencil-cursor 300x300.png",
      "32": "icon 300x300/pencil-cursor 300x300.png",
      "48": "icon 300x300/pencil-cursor 300x300.png"
    }
  },
  "web_accessible_resources": [
    {
      "resources": [
        "assets/*.png",
        "assets/*.svg"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "pencil-window@rojhot.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "tabs",
    "storage",
    "activeTab",
    "scripting"
  ]
}