Introduce FragmentData, and put ObjectPaintProperties into it.

third_party/WebKit/Source/core/paint/FragmentData.h

+// Copyright 2017 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 FragmentData_h
+#define FragmentData_h
+
+#include "core/paint/ObjectPaintProperties.h"
+
+namespace blink {
+
+class ObjectPaintProperties;
+
+// Represents the data for a particular fragment of a LayoutObject.
+// Only LayoutObjects with a self-painting PaintLayer may have more than one
+// FragmentDeta, and even then only when they are inside of multicol.
+// See README.md.
+class FragmentData {
+ public:
+  static std::unique_ptr<FragmentData> Create() {
+    return WTF::WrapUnique(new FragmentData());
+  }
+
+  ObjectPaintProperties* PaintProperties() const {
+    return paint_properties_.get();
+  }
+  ObjectPaintProperties& EnsurePaintProperties();
+  void ClearPaintProperties();
+
+  FragmentData* NextFragment() { return next_fragment_.get(); }
+
+ private:
+  // Holds references to the paint property nodes created by this object.
+  std::unique_ptr<ObjectPaintProperties> paint_properties_;
+
+  std::unique_ptr<FragmentData> next_fragment_;
+};
+
+}  // namespace blink
+
+#endif  // FragmentData_h