Examine source code of Sound Map

{
  "manifest_version": 2,
  "name": "Sound Map",
  "version": "1.3.4",
  "description": "An audio X-ray of any page: headings, links and images become distinct tones. Play the page's structure top to bottom, or enable live mode so scrolling reveals the layout by ear.",
  "icons": {
    "32": "graphics/icon-32.png",
    "48": "graphics/icon-48.png",
    "64": "graphics/icon-64.png",
    "96": "graphics/icon-96.png",
    "128": "graphics/icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{7979a46e-10ad-44ab-8f91-7c6030a0d739}",
      "strict_min_version": "101.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "activeTab",
    "storage"
  ],
  "browser_action": {
    "default_title": "Sound Map",
    "default_popup": "app/popup.html",
    "default_icon": {
      "32": "graphics/icon-32.png",
      "48": "graphics/icon-48.png",
      "64": "graphics/icon-64.png"
    }
  }
}