The "kebab-case" classname of the emitter that raised the event.
Frame is represented as iframe.
The type of event that was raised. Equal to the typename of the event payload in "kebab case".
Guaranteed to be unique within each topic, but can be repeated between topics (e.g. WebContentsEvents.CrashedEvent and ApplicationEvents.CrashedEvent).
Optional error?: Error
Generated when the layout and all of the its views have been created and can receive API calls.