[LayoutNG] Add NGLineBoxFragment

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

Index: third_party/WebKit/Source/core/layout/ng/ng_line_box_fragment_builder.h
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_line_box_fragment_builder.h b/third_party/WebKit/Source/core/layout/ng/ng_line_box_fragment_builder.h
new file mode 100644
index 0000000000000000000000000000000000000000..7606b544b16df332715d947ccdad2fb2e3c05f96
--- /dev/null
+++ b/third_party/WebKit/Source/core/layout/ng/ng_line_box_fragment_builder.h
@@ -0,0 +1,57 @@
+// 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 NGLineBoxFragmentBuilder_h
+#define NGLineBoxFragmentBuilder_h
+
+#include "core/layout/ng/geometry/ng_logical_offset.h"
+#include "core/layout/ng/ng_line_height_metrics.h"
+#include "wtf/Allocator.h"
+
+namespace blink {
+
+class NGInlineNode;
+class NGPhysicalFragment;
+class NGPhysicalLineBoxFragment;
+
+class CORE_EXPORT NGLineBoxFragmentBuilder final {
+  STACK_ALLOCATED();
+
+ public:
+  NGLineBoxFragmentBuilder(NGInlineNode*);
+
+  NGLineBoxFragmentBuilder& SetDirection(TextDirection);
+
+  NGLineBoxFragmentBuilder& SetInlineSize(LayoutUnit);
+
+  NGLineBoxFragmentBuilder& AddChild(RefPtr<NGPhysicalFragment>,
+                                     const NGLogicalOffset&);
+  void MoveChildrenInBlockDirection(LayoutUnit);
+
+  const Vector<RefPtr<NGPhysicalFragment>>& Children() const {
+    return children_;
+  }
+
+  void UniteMetrics(const NGLineHeightMetrics&);
+  const NGLineHeightMetrics& Metrics() const { return metrics_; }
+
+  // Creates the fragment. Can only be called once.
+  RefPtr<NGPhysicalLineBoxFragment> ToLineBoxFragment();
+
+ private:
+  TextDirection direction_;
+
+  Persistent<NGInlineNode> node_;
+
+  LayoutUnit inline_size_;
+
+  Vector<RefPtr<NGPhysicalFragment>> children_;
+  Vector<NGLogicalOffset> offsets_;
+
+  NGLineHeightMetrics metrics_;
+};
+
+}  // namespace blink
+
+#endif  // NGLineBoxFragmentBuilder