Examine source code of KEXP Now Playing

{
  "manifest_version": 2,
  "name": "KEXP Now Playing",
  "version": "1.0.1",
  "description": "An extension that displays what is currently playing on KEXP.org",
  "icons": {
    "192": "logo192.png",
    "512": "logo512.png"
  },
  "browser_action": {
    "default_icon": "logo192.png",
    "default_title": "KEXP Now Playing",
    "default_popup": "index.html"
  }
}