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

third_party/WebKit/Source/core/layout/ng/ng_layout_algorithm.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 NGLayoutAlgorithm_h
 #define NGLayoutAlgorithm_h
 
 #include "core/CoreExport.h"
 #include "wtf/Allocator.h"
 #include "wtf/Noncopyable.h"
@@ skipping 15 matching lines @@
   // Actual layout function. Lays out the children and descendents within the
   // constraints given by the NGConstraintSpace. Returns a fragment with the
   // resulting layout information.
   // This function can not be const because for interruptible layout, we have
   // to be able to store state information.
   // 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.
   virtual bool Layout(NGPhysicalFragment**) = 0;
 
+  enum MinAndMaxState { Success, NotImplemented };

[Gleb Lanbin, 2016/10/31 19:52:47]

may be use std::optional instead of one more enum?

+
+  // Computes the min-content and max-content intrinsic sizes for the given box.
+  // The result will not take any min-width. max-width or width properties into
+  // account. Implementations can return NotImpplemented in which case the
+  // caller is expected ot synthesize this value from the overflow rect returned
+  // from Layout called with a container width of 0 and LayoutUnit::max(),
+  // respectively.
+  virtual MinAndMaxState ComputeMinAndMaxContentSizes(
+      NGFragment** min_content,
+      NGFragment** max_content) {
+    return NotImplemented;
+  }
+
   DEFINE_INLINE_VIRTUAL_TRACE() {}
 };
 
 }  // namespace blink
 
 #endif  // NGLayoutAlgorithm_h