Examine source code of Cozy Equalizer

{
  "manifest_version": 2,
  "name": "Cozy Equalizer",
  "version": "1.6",
  "description": "A simple audio equalizer for web pages with warm, lo-fi presets. Soften the highs, add low-end warmth and gentle saturation with Cozy, Lo-Fi, Warm and Vinyl modes, or tune the bands yourself.",
  "icons": {
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "64": "icons/icon-64.png",
    "96": "icons/icon-96.png",
    "128": "icons/icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d4ceb294-a8ba-4042-86a9-b8a47b461721}",
      "strict_min_version": "101.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "storage",
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "src/eq.js"
      ],
      "run_at": "document_idle",
      "all_frames": true
    }
  ],
  "browser_action": {
    "default_title": "Cozy Equalizer",
    "default_popup": "src/popup.html",
    "default_icon": {
      "32": "icons/icon-32.png",
      "48": "icons/icon-48.png",
      "64": "icons/icon-64.png"
    }
  }
}