[LayoutNG] Abort a layout once the BFC offset is resolved.

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

 // Copyright 2017 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 NGLayoutResult_h
 #define NGLayoutResult_h
 
 #include "core/CoreExport.h"
 #include "core/layout/ng/geometry/ng_static_position.h"
 #include "core/layout/ng/ng_block_node.h"
 #include "core/layout/ng/ng_out_of_flow_positioned_descendant.h"
 #include "core/layout/ng/ng_physical_fragment.h"
 #include "core/layout/ng/ng_unpositioned_float.h"
 #include "platform/LayoutUnit.h"
 #include "platform/heap/Handle.h"
 #include "platform/wtf/RefPtr.h"
 #include "platform/wtf/Vector.h"
 
 namespace blink {
 
 // The NGLayoutResult stores the resulting data from layout. This includes
 // geometry information in form of a NGPhysicalFragment, which is kept around
 // for painting, hit testing, etc., as well as additional data which is only
 // necessary during layout and stored on this object.
 // Layout code should access the NGPhysicalFragment through the wrappers in
 // NGFragment et al.
 class CORE_EXPORT NGLayoutResult : public RefCounted<NGLayoutResult> {
  public:
+  enum NGLayoutResultStatus {
+    kSuccess = 0,
+    kBfcOffsetResolved = 1,
+    // When adding new values, make sure the bit size of |status_| is large
+    // enough to store.
+  };
+
   RefPtr<NGPhysicalFragment> PhysicalFragment() const {
     return physical_fragment_;
   }
+
   RefPtr<NGPhysicalFragment>& MutablePhysicalFragment() {
     return physical_fragment_;
   }
 
   const Vector<NGOutOfFlowPositionedDescendant> OutOfFlowPositionedDescendants()
       const {
     return oof_positioned_descendants_;
   }
 
   // List of floats that need to be positioned by the next in-flow child that
   // can determine its position in space.
   // Use case example where it may be needed:
   //    <div><float></div>
   //    <div style="margin-top: 10px; height: 20px"></div>
   // The float cannot be positioned right away inside of the 1st div because
   // the vertical position is not known at that moment. It will be known only
   // after the 2nd div collapses its margin with its parent.
   const Vector<RefPtr<NGUnpositionedFloat>>& UnpositionedFloats() const {
     return unpositioned_floats_;
   }
 
+  // If...

[eae, 2017/07/10 23:27:49]

Could you expand on this a little bit or remove the comment entirely please?

[ikilpatrick, 2017/07/11 17:20:41]

Done.

+  NGLayoutResultStatus Status() const {
+    return static_cast<NGLayoutResultStatus>(status_);
+  }
+
   const WTF::Optional<NGLogicalOffset>& BfcOffset() const {
     return bfc_offset_;
   }
 
   const NGMarginStrut EndMarginStrut() const { return end_margin_strut_; }
 
  private:
   friend class NGFragmentBuilder;
 
   NGLayoutResult(PassRefPtr<NGPhysicalFragment> physical_fragment,
                  Vector<NGOutOfFlowPositionedDescendant>
                      out_of_flow_positioned_descendants,
                  Vector<RefPtr<NGUnpositionedFloat>>& unpositioned_floats,
                  const WTF::Optional<NGLogicalOffset> bfc_offset,
-                 const NGMarginStrut end_margin_strut);
+                 const NGMarginStrut end_margin_strut,
+                 NGLayoutResultStatus status);
 
   RefPtr<NGPhysicalFragment> physical_fragment_;
   Vector<RefPtr<NGUnpositionedFloat>> unpositioned_floats_;
 
   Vector<NGOutOfFlowPositionedDescendant> oof_positioned_descendants_;
   const WTF::Optional<NGLogicalOffset> bfc_offset_;
   const NGMarginStrut end_margin_strut_;
+
+  unsigned status_ : 1;
 };
 
 }  // namespace blink
 
 #endif  // NGLayoutResult_h