[LayoutNG] Move remaining ng_units structs to their own files

third_party/WebKit/Source/core/layout/ng/ng_min_max_content_size.h

+// 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 MinMaxContentSize_h
+#define MinMaxContentSize_h
+
+#include "core/CoreExport.h"
+#include "core/layout/ng/ng_writing_mode.h"
+#include "platform/LayoutUnit.h"
+
+namespace blink {
+
+struct CORE_EXPORT MinMaxContentSize {
+  LayoutUnit min_content;
+  LayoutUnit max_content;
+  LayoutUnit ShrinkToFit(LayoutUnit available_size) const;
+  bool operator==(const MinMaxContentSize& other) const;
+};
+
+CORE_EXPORT std::ostream& operator<<(std::ostream&, const MinMaxContentSize&);
+
+}  // namespace blink
+
+#endif  // MinMaxContentSize_h