Examine source code of Simple Volume Booster

{
  "manifest_version": 2,
  "name": "Simple Volume Boost",
  "version": "1.2.1",
  "description": "Boost audio volume up to 600% on any tab. Highly optimized with per-site profile saving.",
  "author": "Volume Boost",
  "icons": {
    "48": "icons/icon48.png",
    "96": "icons/icon96.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icons/icon48.png",
      "96": "icons/icon96.png"
    },
    "default_title": "Volume Boost"
  },
  "permissions": [
    "activeTab",
    "tabs",
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle",
      "all_frames": false
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "volume-boost@local",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  }
}