The MessageReceived event occurs when a message is posted
from JavaScript code in the web page using window.chrome.webview.postMessage.
The message is delivered as a string, which can be accessed using the
Message argument. The message may be structured JSON data, or it
may be a simple JSON formatted string. This event provides a two-way
communication channel between the page content and the host
application, allowing developers to implement hybrid scenarios where
the web page can notify the native host of user actions, requests, or
state changes.
If the AllowMessages property is set to False, this
event will not be raised.