Updater: Implement UI

Source/Core/Updater/UI.h

@@ -0,0 +1,19 @@
+// Copyright 2018 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <Windows.h>
+
+namespace UI
+{
+void MessageLoop();
+void Stop();
+
+void SetDescription(const std::string& text);
+void SetMarquee(bool marquee);
+void ResetProgress();
+void SetProgress(int current, int total);
+void IncrementProgress(int amount);
+}  // namespace UI