[layoutng] Add an NGFragmentBuilder

third_party/WebKit/Source/core/layout/ng/ng_fragment_builder.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 NGFragmentBuilder_h
+#define NGFragmentBuilder_h
+
+#include "core/layout/ng/ng_fragment.h"
+#include "core/layout/ng/ng_units.h"
+
+namespace blink {
+
+class CORE_EXPORT NGFragmentBuilder final {
+ public:
+  NGFragmentBuilder(NGFragmentBase::NGFragmentType);
+
+  NGFragmentBuilder& SetWritingMode(NGWritingMode);
+  NGFragmentBuilder& SetDirection(NGDirection);
+
+  NGFragmentBuilder& SetInlineSize(LayoutUnit);
+  NGFragmentBuilder& SetBlockSize(LayoutUnit);
+
+  NGFragmentBuilder& SetInlineOverflow(LayoutUnit);
+  NGFragmentBuilder& SetBlockOverflow(LayoutUnit);
+
+  NGFragmentBuilder& AddChild(const NGFragment*);
+
+  // Offsets are not supposed to be set during fragment construction, so we
+  // do not provide a setter here.
+
+  // Creates the fragment. Can only be called once.
+  NGFragment* ToFragment();
+
+ private:
+  NGFragmentBase::NGFragmentType type_;
+  NGWritingMode writing_mode_;
+  NGDirection direction_;
+
+  NGLogicalSize size_;
+  NGLogicalSize overflow_;
+
+  PersistentHeapVector<Member<const NGFragmentBase>> children_;
+};
+
+}  // namespace blink
+
+#endif  // NGFragmentBuilder