Examine source code of Pitch-Shift Reader

{
  "manifest_version": 2,
  "name": "Pitch-Shift Reader",
  "version": "1.0",
  "description": "Lower pitch of all media elements by 1 semitone for comfortable listening.",
  "permissions": [
    "tabs",
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "icons": {
    "48": "icon48.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{9ed10983-7be6-48a5-aa0d-8efeabe4a4f6}"
    }
  }
}