Improve positioned/percentHeight descendant/container tracking

third_party/WebKit/Source/core/layout/LayoutBox.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 40 matching lines @@
 
 struct LayoutBoxRareData {
     WTF_MAKE_NONCOPYABLE(LayoutBoxRareData); USING_FAST_MALLOC(LayoutBoxRareData);
 public:
     LayoutBoxRareData()
         : m_inlineBoxWrapper(nullptr)
         , m_spannerPlaceholder(nullptr)
         , m_overrideLogicalContentHeight(-1)
         , m_overrideLogicalContentWidth(-1)
         , m_previousBorderBoxSize(-1, -1)
+        , m_percentHeightContainer(nullptr)
     {
     }
 
     // For inline replaced elements, the inline box that owns us.
     InlineBox* m_inlineBoxWrapper;
 
     // For spanners, the spanner placeholder that lays us out within the multicol container.
     LayoutMultiColumnSpannerPlaceholder* m_spannerPlaceholder;
 
     LayoutUnit m_overrideLogicalContentHeight;
     LayoutUnit m_overrideLogicalContentWidth;
 
     // Set by LayoutBox::savePreviousBoxSizesIfNeeded().
     LayoutSize m_previousBorderBoxSize;
     LayoutRect m_previousContentBoxRect;
     LayoutRect m_previousLayoutOverflowRect;
 
     LayoutUnit m_pageLogicalOffset;
 
     LayoutUnit m_paginationStrut;
+
+    LayoutBlock* m_percentHeightContainer;
 };
 
 // LayoutBox implements the full CSS box model.
 //
 // LayoutBoxModelObject only introduces some abstractions for LayoutInline and
 // LayoutBox. The logic for the model is in LayoutBox, e.g. the storage for the
 // rectangle and offset forming the CSS box (m_frameRect) and the getters for
 // the different boxes.
 //
 // LayoutBox is also the uppermost class to support scrollbars, however the
@@ skipping 751 matching lines @@
 
     void setIntrinsicContentLogicalHeight(LayoutUnit intrinsicContentLogicalHeight) const { m_intrinsicContentLogicalHeight = intrinsicContentLogicalHeight; }
 
     bool canRenderBorderImage() const;
 
     void mapLocalToAncestor(const LayoutBoxModelObject* ancestor, TransformState&, MapCoordinatesFlags = ApplyContainerFlip, bool* wasFixed = nullptr, const PaintInvalidationState* = nullptr) const override;
     void mapAbsoluteToLocalPoint(MapCoordinatesFlags, TransformState&) const override;
 
     void clearPreviousPaintInvalidationRects() override;
 
+    LayoutBlock* percentHeightContainer() const { return m_rareData ? m_rareData->m_percentHeightContainer : nullptr; }
+    void setPercentHeightContainer(LayoutBlock*);
+    void removeFromPercentHeightContainer();
+    void clearPercentHeightDescendants();
+
 protected:
     void willBeDestroyed() override;
 
     void styleWillChange(StyleDifference, const ComputedStyle& newStyle) override;
     void styleDidChange(StyleDifference, const ComputedStyle* oldStyle) override;
     void updateFromStyle() override;
 
     // Returns false if it could not cheaply compute the extent (e.g. fixed background), in which case the returned rect may be incorrect.
     // FIXME: make this a const method once the LayoutBox reference in BoxPainter is const.
     bool getBackgroundPaintedExtent(LayoutRect&) const;
@@ skipping 205 matching lines @@
         if (UNLIKELY(inlineBoxWrapper() != nullptr))
             deleteLineBoxWrapper();
     }
 
     ensureRareData().m_inlineBoxWrapper = boxWrapper;
 }
 
 } // namespace blink
 
 #endif // LayoutBox_h