Examine source code of Libre Note

{
  "manifest_version": 2,
  "name": "Libre Note",
  "version": "0.0.1",
  "description": "Simple Note Taking extension.",
  "icons": {
    "48": "images/logo-48.png",
    "96": "images/logo-96.png"
  },
  "permissions": [
    "storage",
    "unlimitedStorage"
  ],
  "browser_action": {
    "default_icon": "images/logo-48.png",
    "default_title": "Libre Note",
    "default_popup": "main.html"
  }
}