Demo patch that demonstrates simple block layout using Layout NG

third_party/WebKit/Source/core/layout/ng/ng_box.cc

Index: third_party/WebKit/Source/core/layout/ng/ng_box.cc
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_box.cc b/third_party/WebKit/Source/core/layout/ng/ng_box.cc
index 7f8a30fa105500bd6dd3abbdf290f4cbd5451c08..54c6bcd73db420c7a9a1efccb1ba26bbd5791a67 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_box.cc
+++ b/third_party/WebKit/Source/core/layout/ng/ng_box.cc
@@ -6,24 +6,23 @@
 
 #include "core/layout/LayoutObject.h"
 #include "core/layout/ng/ng_block_layout_algorithm.h"
+#include "core/layout/ng/ng_fragment.h"
+#include "core/layout/LayoutBox.h"
 
 namespace blink {
 
 NGFragment* NGBox::layout(const NGConstraintSpace& constraintSpace) {
-  NGBlockLayoutAlgorithm algorithm(style(), firstChild());
-  return algorithm.layout(constraintSpace);
+  NGBlockLayoutAlgorithm algorithm(style(), iterator());
+  m_layoutObject->clearNeedsLayout();
+  NGFragment* fragement = algorithm.layout(constraintSpace);
+  DCHECK(m_layoutObject->isBox());
+  toLayoutBox(m_layoutObject)->setLogicalWidth(fragement->inlineSize());

[eae, 2016/08/11 15:40:49]

We probably want to add a fragment->size method and use
setLogicalSize(fragment->size()). Let's do that in a separate CL though.

[Gleb Lanbin, 2016/08/11 16:08:16]

Acknowledged.

+  toLayoutBox(m_layoutObject)->setLogicalHeight(fragement->blockSize());
+  return fragement;
 }
 
 const ComputedStyle* NGBox::style() const {
   return m_layoutObject->style();
 }
 
-const NGBox NGBox::firstChild() const {
-  return NGBox(m_layoutObject->slowFirstChild());
-}
-
-const NGBox NGBox::nextSibling() const {
-  return NGBox(m_layoutObject->nextSibling());
-}
-
 }  // namespace blink