QtWebEngineProcess.exe doesn't automatically stops if close QDialog with web content

#include <QApplication>
#include <QWebEngineView>
#include <QWebEngineSettings>
#include <QDialog>
#include <QMainWindow>
#include <QLayout>
#include <QtGui>
#include <QPushButton>

class Dialog : public QDialog
{
public:
    Dialog() : QDialog(nullptr)
    {
        resize(512, 512);
        setAttribute(Qt::WA_DeleteOnClose);
        auto verticalLayout = new QVBoxLayout(this);
        verticalLayout->setSpacing(0);
        verticalLayout->setContentsMargins(0, 0, 0, 0);

        m_webView = new QWebEngineView(this);
        verticalLayout->addWidget(m_webView);
    }

    void openPage(const QUrl& url)
    {
        m_webView->setUrl(url);
    }

private:
    QWebEngineView* m_webView;
};


class MainWindow : public QMainWindow
{
public:
    MainWindow() : QMainWindow(nullptr)
    {
        resize(512, 512);
        QPushButton* btn = new QPushButton("open web dialog", this);
        connect(btn, &QPushButton::clicked, [this] ()
                {
                    if (m_dialog == nullptr)
                    {
                        m_dialog = new Dialog();
                        m_dialog->openPage(QUrl("https://www.qt.io"));
                        m_dialog->show();
                    }
                });
    }

private:
    QPointer<Dialog> m_dialog;

};

int main(int argc, char *argv[])
{
    QCoreApplication::setOrganizationName("QtExamples");
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QApplication app(argc, argv);

    MainWindow window;
    window.show();

    return app.exec();
}