Callback Triggers
These functions call callbacks, used for tests…
closing(page)initialized()javaScriptAlertSent(message)javaScriptConsoleMessageSent(message)loadFinished(status)loadStarted()navigationRequested(url, navigationType, navigationLocked, isMainFrame)rawPageCreated(page)resourceError(resource)resourceReceived(request)resourceRequested(resource)urlChanged(url)