Import Cobalt 24.master.0.1033952
diff --git a/ui/gfx/win/rendering_window_manager.h b/ui/gfx/win/rendering_window_manager.h
new file mode 100644
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+++ b/ui/gfx/win/rendering_window_manager.h
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+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_GFX_WIN_RENDERING_WINDOW_MANAGER_H_
+#define UI_GFX_WIN_RENDERING_WINDOW_MANAGER_H_
+
+#include <windows.h>
+
+#include "base/containers/flat_map.h"
+#include "base/memory/scoped_refptr.h"
+#include "base/no_destructor.h"
+#include "ui/gfx/gfx_export.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace gfx {
+
+// This keeps track of whether a given HWND has a child window which the GPU
+// process renders into. This should only be used from the UI thread unless
+// otherwise noted.
+class GFX_EXPORT RenderingWindowManager {
+ public:
+ // The first call to GetInstance() should happen on the UI thread.
+ static RenderingWindowManager* GetInstance();
+
+ RenderingWindowManager(const RenderingWindowManager&) = delete;
+ RenderingWindowManager& operator=(const RenderingWindowManager&) = delete;
+
+ void RegisterParent(HWND parent);
+ // Registers |child| as child window for |parent|. Allows the GPU process to
+ // draw into the |child| HWND instead of |parent|. This will fail and do
+ // nothing if:
+ // 1. |parent| isn't registered.
+ // 2. |child| doesn't belong to |expected_child_process_id|.
+ //
+ // Can be called from any thread, as long GetInstance() has already been
+ // called on the UI thread at least once.
+ void RegisterChild(HWND parent, HWND child, DWORD expected_child_process_id);
+ void UnregisterParent(HWND parent);
+ bool HasValidChildWindow(HWND parent);
+
+ private:
+ friend class base::NoDestructor<RenderingWindowManager>;
+
+ RenderingWindowManager();
+ ~RenderingWindowManager();
+
+ // UI thread task runner.
+ scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+ // Map from registered parent HWND to child HWND.
+ base::flat_map<HWND, HWND> registered_hwnds_;
+};
+
+} // namespace gfx
+
+#endif // UI_GFX_WIN_RENDERING_WINDOW_MANAGER_H_
