Examine source code of DropTop

{
  "name": "DropTop",
  "version": "2.0",
  "manifest_version": 2,
  "description": "Share small snippets of data between devices",
  "permissions": [
    "storage",
    "tabs",
    "clipboardWrite"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "DropTop"
  },
  "icons": {
    "16": "assets/icons/icon-16x16.png",
    "32": "assets/icons/icon-32x32.png",
    "48": "assets/icons/icon-48x48.png",
    "128": "assets/icons/icon-128x128.png"
  }
}