[layoutng] Support computing min-content and max-content

third_party/WebKit/Source/core/layout/ng/ng_box.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 NGBox_h
 #define NGBox_h
 
 #include "core/CoreExport.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
 class ComputedStyle;
 class LayoutBox;
 class LayoutObject;
-class NGBlockLayoutAlgorithm;
 class NGConstraintSpace;
 class NGFragment;
+class NGLayoutAlgorithm;
 class NGPhysicalFragment;
+struct MinAndMaxContentSizes;
 
 // Represents a node to be laid out.
 class CORE_EXPORT NGBox final : public GarbageCollectedFinalized<NGBox> {
  public:
   explicit NGBox(LayoutObject*);
 
   // TODO(layout-ng): make it private and declare a friend class to use in tests
   explicit NGBox(ComputedStyle*);
 
   // Returns true when done; when this function returns false, it has to be
   // called again. The out parameter will only be set when this function
   // returns true. The same constraint space has to be passed each time.
   // TODO(layout-ng): Should we have a StartLayout function to avoid passing
   // the same space for each Layout iteration?
   bool Layout(const NGConstraintSpace*, NGFragment**);
+
+  // Computes the value of min-content and max-content for this box.
+  // The return value has the same meaning as for Layout.
+  // If the underlying layout algorithm returns NotImplemented from
+  // ComputeMinAndMaxContentSizes, this function will synthesize these sizes
+  // using Layout with special constraint spaces.
+  // It is not legal to interleave a pending Layout() with a pending
+  // ComputeOrSynthesizeMinAndMaxContentSizes (i.e. you have to call Layout
+  // often enough that it returns true before calling
+  // ComputeOrSynthesizeMinAndMaxContentSizes)
+  bool ComputeMinAndMaxContentSizes(MinAndMaxContentSizes*);
+
   const ComputedStyle* Style() const;
 
   NGBox* NextSibling();
 
   NGBox* FirstChild();
 
   void SetNextSibling(NGBox*);
   void SetFirstChild(NGBox*);
 
-  DEFINE_INLINE_VIRTUAL_TRACE() {
-    visitor->trace(algorithm_);
-    visitor->trace(fragment_);
-    visitor->trace(next_sibling_);
-    visitor->trace(first_child_);
-  }
+  DECLARE_VIRTUAL_TRACE();
 
  private:
   // This is necessary for interop between old and new trees -- after our parent
   // positions us, it calls this function so we can store the position on the
   // underlying LayoutBox.
   void PositionUpdated();
 
   bool CanUseNewLayout();
 
   // After we run the layout algorithm, this function copies back the geometry
   // data to the layout box.
   void CopyFragmentDataToLayoutBox(const NGConstraintSpace&);
 
   // Runs layout on layout_box_ and creates a fragment for the resulting
   // geometry.
   NGPhysicalFragment* RunOldLayout(const NGConstraintSpace&);
 
   // We can either wrap a layout_box_ or a style_/next_sibling_/first_child_
   // combination.
   LayoutBox* layout_box_;
   RefPtr<ComputedStyle> style_;
   Member<NGBox> next_sibling_;
   Member<NGBox> first_child_;
-  Member<NGBlockLayoutAlgorithm> algorithm_;
+  Member<NGLayoutAlgorithm> layout_algorithm_;
+  Member<NGLayoutAlgorithm> minmax_algorithm_;
   Member<NGPhysicalFragment> fragment_;
 };
 
 }  // namespace blink
 
 #endif  // NGBox_h