Examine source code of FF Sound Booster

{
  "manifest_version": 2,
  "name": "FF Sound Booster",
  "version": "1.1.0",
  "description": "Boost audio volume beyond 100% on any webpage using the Web Audio API.",
  "author": "Lenkura",
  "permissions": [
    "storage",
    "activeTab",
    "tabs"
  ],
  "browser_action": {
    "default_popup": "popup/popup.html",
    "default_title": "FF Sound Booster",
    "default_icon": {
      "16": "icons/icon-16.png",
      "48": "icons/icon-48.png",
      "128": "icons/icon-128.png"
    }
  },
  "icons": {
    "16": "icons/icon-16.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content/content.js"
      ],
      "run_at": "document_idle",
      "all_frames": true
    }
  ],
  "content_security_policy": "script-src 'self'; object-src 'self'",
  "browser_specific_settings": {
    "gecko": {
      "id": "ffsoundbooster@lenkura",
      "strict_min_version": "58.0"
    }
  }
}