Examine source code of WebSonic

{
  "manifest_version": 2,
  "name": "WebSonic",
  "version": "1.0.10",
  "description": "This extension provides auditory feedback for many browser events",
  "homepage_url": "https://techromantica.com/WebSonic/",
  "icons": {
    "16": "icons/16.png",
    "32": "icons/32.png",
    "48": "icons/48.png",
    "96": "icons/96.png",
    "128": "icons/128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "websonic@techromantica.com",
      "strict_min_version": "75.0"
    }
  },
  "browser_action": {
    "default_title": "WebSonic",
    "default_popup": "options.html",
    "default_icon": {
      "16": "icons/16.png",
      "32": "icons/32.png",
      "48": "icons/48.png",
      "96": "icons/96.png",
      "128": "icons/128.png"
    }
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "background": {
    "page": "background.html"
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Alt+Shift+W",
        "windows": "Alt+Shift+W"
      },
      "description": "Open WebSonic Settings",
      "global": true
    }
  },
  "permissions": [
    "webNavigation",
    "downloads",
    "bookmarks",
    "storage"
  ],
  "content_security_policy": "script-src 'self'; object-src 'self'",
  "default_locale": "en"
}