video_core: add null backend

src/yuzu_cmd/emu_window/emu_window_sdl2_null.h

@@ -0,0 +1,26 @@
+// SPDX-FileCopyrightText: Copyright 2022 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <memory>
+
+#include "core/frontend/emu_window.h"
+#include "yuzu_cmd/emu_window/emu_window_sdl2.h"
+
+namespace Core {
+class System;
+}
+
+namespace InputCommon {
+class InputSubsystem;
+}
+
+class EmuWindow_SDL2_Null final : public EmuWindow_SDL2 {
+public:
+    explicit EmuWindow_SDL2_Null(InputCommon::InputSubsystem* input_subsystem_,
+                                 Core::System& system, bool fullscreen);
+    ~EmuWindow_SDL2_Null() override;
+
+    std::unique_ptr<Core::Frontend::GraphicsContext> CreateSharedContext() const override;
+};