UI: Split out Whats New dialog, fix crash on shutdown

CEF crashes on shutdown if any browser window remains open during the
shutdown flow. Reproducible 100% of the time on Linux with What's New.
The previous implementation of the What's New dialog correctly deleted
all the Qt widgets, but the CEF internal event flow would only call the
"preparing to close" function, and never the "window safely closed"
function. Moving the code (practically unchanged) to a custom QDialog
solves the problem entirely, and is more consistent with other uses.

UI/cmake/ui-windows.cmake

@@ -58,4 +58,6 @@ target_sources(
     window-projector.hpp
     window-remux.cpp
     window-remux.hpp
+    window-whats-new.cpp
+    window-whats-new.hpp
 )

UI/window-basic-main.cpp

@@ -68,6 +68,7 @@
 #include "window-youtube-actions.hpp"
 #include "youtube-api-wrappers.hpp"
 #endif
+#include "window-whats-new.hpp"
 #include "context-bar-controls.hpp"
 #include "obs-proxy-style.hpp"
 #include "display-helpers.hpp"
@@ -128,6 +129,8 @@ void DestroyPanelCookieManager();
 
 namespace {
 
+QPointer<OBSWhatsNew> obsWhatsNew;
+
 template<typename OBSRef> struct SignalContainer {
 	OBSRef ref;
 	vector<shared_ptr<OBSSignal>> handlers;
@@ -2544,37 +2547,11 @@ void OBSBasic::ShowWhatsNew(const QString &url)
 	if (closing)
 		return;
 
-	std::string info_url = QT_TO_UTF8(url);
-
-	QDialog *dlg = new QDialog(this);
-	dlg->setAttribute(Qt::WA_DeleteOnClose, true);
-	dlg->setWindowTitle("What's New");
-	dlg->resize(700, 600);
-
-	Qt::WindowFlags flags = dlg->windowFlags();
-	Qt::WindowFlags helpFlag = Qt::WindowContextHelpButtonHint;
-	dlg->setWindowFlags(flags & (~helpFlag));
-
-	QCefWidget *cefWidget = cef->create_widget(nullptr, info_url);
-	if (!cefWidget) {
-		return;
+	if (obsWhatsNew) {
+		obsWhatsNew->close();
 	}
 
-	connect(cefWidget, &QCefWidget::titleChanged, dlg, &QDialog::setWindowTitle);
-
-	QPushButton *close = new QPushButton(QTStr("Close"));
-	connect(close, &QAbstractButton::clicked, dlg, &QDialog::accept);
-
-	QHBoxLayout *bottomLayout = new QHBoxLayout();
-	bottomLayout->addStretch();
-	bottomLayout->addWidget(close);
-	bottomLayout->addStretch();
-
-	QVBoxLayout *topLayout = new QVBoxLayout(dlg);
-	topLayout->addWidget(cefWidget);
-	topLayout->addLayout(bottomLayout);
-
-	dlg->show();
+	obsWhatsNew = new OBSWhatsNew(this, QT_TO_UTF8(url));
 #else
 	UNUSED_PARAMETER(url);
 #endif

UI/window-whats-new.cpp

@@ -0,0 +1,74 @@
+#include "moc_window-whats-new.cpp"
+
+#include <QPushButton>
+#include <QHBoxLayout>
+#include <QVBoxLayout>
+
+#include "window-basic-main.hpp"
+
+#ifdef BROWSER_AVAILABLE
+#include <browser-panel.hpp>
+extern QCef *cef;
+#endif
+
+/* ------------------------------------------------------------------------- */
+
+OBSWhatsNew::OBSWhatsNew(QWidget *parent, const std::string &url) : QDialog(parent)
+{
+#ifdef BROWSER_AVAILABLE
+	if (!cef) {
+		return;
+	}
+
+	setWindowTitle("What's New");
+	setAttribute(Qt::WA_DeleteOnClose, true);
+	resize(700, 600);
+
+	Qt::WindowFlags flags = windowFlags();
+	Qt::WindowFlags helpFlag = Qt::WindowContextHelpButtonHint;
+	setWindowFlags(flags & (~helpFlag));
+
+	OBSBasic::InitBrowserPanelSafeBlock();
+
+	cefWidget = cef->create_widget(nullptr, url);
+	if (!cefWidget) {
+		return;
+	}
+
+	connect(cefWidget, &QCefWidget::titleChanged, this, &OBSWhatsNew::setWindowTitle);
+
+	QPushButton *close = new QPushButton(QTStr("Close"));
+	connect(close, &QAbstractButton::clicked, this, &QDialog::accept);
+
+	QHBoxLayout *bottomLayout = new QHBoxLayout();
+	bottomLayout->addStretch();
+	bottomLayout->addWidget(close);
+	bottomLayout->addStretch();
+
+	QVBoxLayout *topLayout = new QVBoxLayout(this);
+	topLayout->addWidget(cefWidget);
+	topLayout->addLayout(bottomLayout);
+
+	show();
+#else
+	UNUSED_PARAMETER(url);
+#endif
+}
+
+OBSWhatsNew::~OBSWhatsNew() {}
+
+void OBSWhatsNew::reject()
+{
+#ifdef BROWSER_AVAILABLE
+	delete cefWidget;
+#endif
+	QDialog::reject();
+}
+
+void OBSWhatsNew::accept()
+{
+#ifdef BROWSER_AVAILABLE
+	delete cefWidget;
+#endif
+	QDialog::accept();
+}

UI/window-whats-new.hpp

@@ -0,0 +1,20 @@
+#pragma once
+
+#include <QPointer>
+#include <QDialog>
+#include <string>
+
+class QCefWidget;
+
+class OBSWhatsNew : public QDialog {
+	Q_OBJECT
+
+	QCefWidget *cefWidget = nullptr;
+
+public:
+	OBSWhatsNew(QWidget *parent, const std::string &url);
+	~OBSWhatsNew();
+
+	virtual void reject() override;
+	virtual void accept() override;
+};