[UI] Use game icon as the app icon -- fix regression introduced by Qt

src/xenia/ui/window_qt.cc

@@ -13,9 +13,11 @@
 #include <QCloseEvent>
 #include <QCursor>
 #include <QGuiApplication>
+#include <QIcon>
 #include <QKeyEvent>
 #include <QMenuBar>
 #include <QMouseEvent>
+#include <QPixmap>
 #include <QResizeEvent>
 #include <QThread>
 #include <QTimer>
@@ -282,6 +284,28 @@ void QtWindow::ApplyNewTitle() {
   }
 }
 
+void QtWindow::LoadAndApplyIcon(const void* buffer, size_t size,
+                                bool can_apply_state_in_current_phase) {
+  if (!qwindow_) {
+    return;
+  }
+
+  bool reset = !buffer || !size;
+
+  if (reset) {
+    // Reset to default/no icon
+    qwindow_->setWindowIcon(QIcon());
+  } else {
+    // Load icon from buffer (typically from game executable)
+    QPixmap pixmap;
+    if (pixmap.loadFromData(static_cast<const uchar*>(buffer),
+                            static_cast<uint>(size))) {
+      QIcon icon(pixmap);
+      qwindow_->setWindowIcon(icon);
+    }
+  }
+}
+
 void QtWindow::ApplyNewMainMenu(MenuItem* old_main_menu) {
   if (!qwindow_) return;
 

src/xenia/ui/window_qt.h

@@ -50,6 +50,8 @@ class QtWindow : public Window {
 
   void ApplyNewFullscreen() override;
   void ApplyNewTitle() override;
+  void LoadAndApplyIcon(const void* buffer, size_t size,
+                        bool can_apply_state_in_current_phase) override;
   void ApplyNewMainMenu(MenuItem* old_main_menu) override;
   void ApplyNewCursorVisibility(
       CursorVisibility old_cursor_visibility) override;