[ Version ( since = "2.28" ) ]
public signal void user_message_received (UserMessage message)
This signal is emitted when a UserMessage is received from the WebKitWebContext
corresponding to extension.
Messages sent by WebKitWebContext are always broadcasted to all
WebExtension<!-- -->s and they can't be replied to. Calling
send_reply will do nothing.
| message |
the UserMessage received |