telemetry and timing updates

apps/RenderCadenceCompositor/frames/SystemFrameExchange.h

@@ -40,6 +40,8 @@ private:
 	};
 
 	bool AcquireFreeLocked(SystemFrame& frame);
+	bool DropOldestCompletedLocked();
+	void TrimCompletedLocked();
 	bool IsValidLocked(const SystemFrame& frame) const;
 	void FillFrameLocked(std::size_t index, SystemFrame& frame);
 	std::size_t CompletedCountLocked() const;