[layoutng] Make the layout algorithm actually compute and store positions and sizes

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

 // 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.
 
 #include "core/layout/ng/ng_block_layout_algorithm.h"
 
 #include "core/layout/LayoutBox.h"
 #include "core/layout/ng/ng_constraint_space.h"
 #include "core/layout/ng/ng_fragment.h"
 #include "core/layout/ng/ng_length_utils.h"
 #include "core/style/ComputedStyle.h"
 #include "platform/LengthFunctions.h"
 
 namespace blink {
 
 NGBlockLayoutAlgorithm::NGBlockLayoutAlgorithm(
     PassRefPtr<const ComputedStyle> style,
     NGBox firstChild)
     : m_style(style), m_firstChild(firstChild) {}
 
 NGFragment* NGBlockLayoutAlgorithm::layout(
     const NGConstraintSpace& constraintSpace) {
   LayoutUnit inlineSize =
       computeInlineSizeForFragment(constraintSpace, *m_style);
 
+  HeapVector<Member<const NGFragmentBase>> childFragments;
+
+  LayoutUnit contentSize;
   for (NGBox curr = m_firstChild; curr; curr.nextSibling()) {
-    curr.layout(constraintSpace);
+    NGFragment* fragment = curr.layout(constraintSpace);
+    // TODO(layout-ng): Take margins into account
+    fragment->setOffset(LayoutUnit(), contentSize);
+    contentSize += fragment->blockSize();
+    childFragments.append(fragment);
   }
 
   LayoutUnit blockSize =
-      computeBlockSizeForFragment(constraintSpace, *m_style, LayoutUnit());
-  return new NGFragment(inlineSize, blockSize, inlineSize, blockSize);
+      computeBlockSizeForFragment(constraintSpace, *m_style, contentSize);
+  NGFragment* returnFragment =
+      new NGFragment(inlineSize, blockSize, inlineSize, blockSize);
+  returnFragment->swapChildren(childFragments);
+  return returnFragment;
 }
 
 }  // namespace blink