Add (untested) Steam Link video decoding/rendering

app/streaming/video/sl.h

@@ -0,0 +1,28 @@
+#pragma once
+
+#include "decoder.h"
+
+#include <SLVideo.h>
+
+class SLVideoDecoder : public IVideoDecoder
+{
+public:
+    SLVideoDecoder();
+    virtual ~SLVideoDecoder();
+    virtual bool initialize(StreamingPreferences::VideoDecoderSelection vds,
+                            SDL_Window* window,
+                            int videoFormat,
+                            int width,
+                            int height,
+                            int frameRate);
+    virtual bool isHardwareAccelerated();
+    virtual int submitDecodeUnit(PDECODE_UNIT du);
+
+    // Unused since rendering is done directly from the decode thread
+    virtual void renderFrame(SDL_UserEvent*) {}
+    virtual void dropFrame(SDL_UserEvent*) {}
+
+private:
+    CSLVideoContext* m_VideoContext;
+    CSLVideoStream* m_VideoStream;
+};