Examine source code of Transpose

{
  "manifest_version": 2,
  "name": "Transpose",
  "version": "1.0.0",
  "description": "Adjust transpose, pitch, and speed of audio/video playing in Firefox.",
  "browser_specific_settings": {
    "gecko": {
      "id": "transpose@rjsec",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  },
  "icons": {
    "16": "icons/icon-16.svg",
    "48": "icons/icon-48.svg",
    "128": "icons/icon-128.svg"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Transpose",
    "default_icon": {
      "16": "icons/icon-16.svg",
      "48": "icons/icon-48.svg",
      "128": "icons/icon-128.svg"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "permissions": [
    "activeTab",
    "tabs",
    "storage"
  ],
  "web_accessible_resources": [
    "pitch-processor.js"
  ]
}