More work. Audio driver works enough to play music now.

GpCommon/IGpDisplayDriver.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include "PixelFormat.h"
+
+// Display drivers are responsible for timing and calling the game tick function.
+class IGpDisplayDriver
+{
+public:
+	virtual ~IGpDisplayDriver() {}
+
+	virtual void Run() = 0;
+	virtual void Shutdown() = 0;
+
+	virtual void GetDisplayResolution(unsigned int *width, unsigned int *height, PortabilityLayer::PixelFormat *bpp) = 0;
+};