Add performance overlay for DXVA2 renderer

app/streaming/video/overlaymanager.h

@@ -0,0 +1,26 @@
+#pragma once
+
+#include <QString>
+
+class OverlayManager
+{
+public:
+    enum OverlayType {
+        OverlayDebug,
+        OverlayMinorNotification,
+        OverlayMajorNotification,
+        OverlayMax
+    };
+
+    OverlayManager();
+
+    bool isOverlayEnabled(OverlayType type);
+    char* getOverlayText(OverlayType type);
+    void setOverlayState(OverlayType type, bool enabled);
+
+    struct {
+        bool enabled;
+        int updateSeq;
+        char text[512];
+    } m_Overlays[OverlayMax];
+};