Demo patch that demonstrates simple block layout using Layout NG

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

Index: third_party/WebKit/Source/core/layout/ng/ng_box_iterator.h
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_box_iterator.h b/third_party/WebKit/Source/core/layout/ng/ng_box_iterator.h
new file mode 100644
index 0000000000000000000000000000000000000000..55df0d412d073aabad8c24045bbab81c08a179a9
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+++ b/third_party/WebKit/Source/core/layout/ng/ng_box_iterator.h
@@ -0,0 +1,38 @@
+// 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 NGBoxIterator_h
+#define NGBoxIterator_h
+
+#include "core/layout/LayoutObject.h"
+
+namespace blink {
+
+class NGBox;
+
+// NG Box iterator over siblings of the layout object.
+class NGBoxIterator : public std::iterator<std::forward_iterator_tag, NGBox> {
+ public:
+  class iterator {
+   public:
+    iterator& operator=(const iterator& otherValue);
+    iterator(LayoutObject* layoutObject) : m_layoutObject(layoutObject) {}
+    iterator& operator++();
+    bool operator!=(const iterator& other);
+    NGBox operator*();
+
+   private:
+    LayoutObject* m_layoutObject;
+  };
+  explicit NGBoxIterator(LayoutObject*);
+
+  iterator begin() const { return iterator(m_layoutObject->slowFirstChild()); }
+  iterator end() const { return iterator(nullptr); }
+
+ private:
+  LayoutObject* m_layoutObject;
+};
+
+}  // namespace blink
+#endif  // NGBoxIterator_h