Examine source code of ScanToSong

{
  "manifest_version": 2,
  "name": "ScanToSong",
  "version": "1.0",
  "description": "Scans current page for unplayed audio links (.mp3/.wav/stream) and lists them with play/download options and 5s preview.",
  "permissions": [
    "activeTab",
    "storage"
  ],
  "browser_action": {
    "default_title": "ScanToSong",
    "default_popup": "popup.html"
  },
  "applications": {
    "gecko": {
      "id": "scantosong@example.com"
    }
  }
}