Introduce NGFloatingObject

third_party/WebKit/Source/core/layout/ng/ng_floating_object.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 NGFloatingObject_h
+#define NGFloatingObject_h
+
+#include "core/layout/ng/ng_block_node.h"
+#include "core/layout/ng/ng_constraint_space.h"
+#include "core/layout/ng/ng_units.h"
+#include "core/style/ComputedStyle.h"
+#include "core/style/ComputedStyleConstants.h"
+#include "platform/heap/Handle.h"
+
+namespace blink {
+
+class NGPhysicalFragment;
+
+// Struct that keeps all information needed to position floats in LayoutNG.
+struct CORE_EXPORT NGFloatingObject
+    : public GarbageCollected<NGFloatingObject> {
+  NGFloatingObject(NGPhysicalFragment* fragment,
+                   const NGConstraintSpace* space,
+                   NGBlockNode* node,
+                   const ComputedStyle& style)
+      : fragment(fragment), space(space), node(node) {
+    exclusion_type = NGExclusion::kFloatLeft;
+    if (style.floating() == EFloat::kRight)
+      exclusion_type = NGExclusion::kFloatRight;
+    clear_type = style.clear();
+  }
+
+  Member<NGPhysicalFragment> fragment;
+  Member<const NGConstraintSpace> space;
+  // TODO(ikilpatrick): remove this.
+  Member<NGBlockNode> node;

[ikilpatrick, 2017/01/20 18:11:14]

I think this should be a WeakMember?

NGBlockNode -> Fragment -> NGFloatingObject -> NGBlockNode?

Also i realize from our discussion yesterday that if we end up doing this
post-layout that todo is irrelevant.

[Gleb Lanbin, 2017/01/20 21:21:59]

according to Oilpan documentation it's better to use Member here because
- use of WeakMember<T> incurs some overhead in garbage collector's performance
- weak members are not necessary at all, because reference cycles with members
are allowed
- WeakMember<T> should be used only if the owner of a weak member can outlive
the pointed object.

https://chromium.googlesource.com/chromium/src/+/master/third_party/WebKit/So...

+  NGExclusion::Type exclusion_type;
+  EClear clear_type;
+
+  DEFINE_INLINE_TRACE() {
+    visitor->trace(fragment);
+    visitor->trace(space);
+    visitor->trace(node);
+  }
+};
+
+}  // namespace blink
+
+#endif  // NGFloatingObject_h