Adapt and reland old position sticky implementation

third_party/WebKit/Source/core/page/scrolling/ScrollingConstraints.h

Index: third_party/WebKit/Source/core/page/scrolling/ScrollingConstraints.h
diff --git a/third_party/WebKit/Source/core/page/scrolling/ScrollingConstraints.h b/third_party/WebKit/Source/core/page/scrolling/ScrollingConstraints.h
deleted file mode 100644
index 6b3dca6ed15f4f13cb52653d392476c18f874ecc..0000000000000000000000000000000000000000
--- a/third_party/WebKit/Source/core/page/scrolling/ScrollingConstraints.h
+++ /dev/null
@@ -1,118 +0,0 @@
-/*
- * Copyright (C) 2012 Apple Inc. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
- * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
- * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
- * THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#ifndef ScrollingConstraints_h
-#define ScrollingConstraints_h
-
-#include "platform/geometry/FloatRect.h"
-#include "wtf/Allocator.h"
-
-namespace blink {
-
-// ViewportConstraints classes encapsulate data and logic required to reposition elements whose layout
-// depends on the viewport rect (i.e., position fixed), when scrolling and zooming.
-class ViewportConstraints {
-    STACK_ALLOCATED();
-public:
-    // FIXME: Simplify this code now that position: sticky doesn't exist.
-    enum ConstraintType {
-        FixedPositionConstaint,
-    };
-
-    enum AnchorEdgeFlags {
-        AnchorEdgeLeft = 1 << 0,
-        AnchorEdgeRight = 1 << 1,
-        AnchorEdgeTop = 1 << 2,
-        AnchorEdgeBottom = 1 << 3
-    };
-    typedef unsigned AnchorEdges;
-
-    ViewportConstraints(const ViewportConstraints& other)
-        : m_alignmentOffset(other.m_alignmentOffset)
-        , m_anchorEdges(other.m_anchorEdges)
-    { }
-
-    virtual ~ViewportConstraints() { }
-
-    virtual ConstraintType constraintType() const = 0;
-
-    AnchorEdges anchorEdges() const { return m_anchorEdges; }
-    bool hasAnchorEdge(AnchorEdgeFlags flag) const { return m_anchorEdges & flag; }
-    void addAnchorEdge(AnchorEdgeFlags edgeFlag) { m_anchorEdges |= edgeFlag; }
-    void setAnchorEdges(AnchorEdges edges) { m_anchorEdges = edges; }
-
-    FloatSize alignmentOffset() const { return m_alignmentOffset; }
-    void setAlignmentOffset(const FloatSize& offset) { m_alignmentOffset = offset; }
-
-protected:
-    ViewportConstraints()
-        : m_anchorEdges(0)
-    { }
-
-    FloatSize m_alignmentOffset;
-    AnchorEdges m_anchorEdges;
-};
-
-class FixedPositionViewportConstraints final : public ViewportConstraints {
-    STACK_ALLOCATED();
-public:
-    FixedPositionViewportConstraints()
-        : ViewportConstraints()
-    { }
-
-    FixedPositionViewportConstraints(const FixedPositionViewportConstraints& other)
-        : ViewportConstraints(other)
-        , m_viewportRectAtLastLayout(other.m_viewportRectAtLastLayout)
-        , m_layerPositionAtLastLayout(other.m_layerPositionAtLastLayout)
-    { }
-
-    FloatPoint layerPositionForViewportRect(const FloatRect& viewportRect) const;
-
-    const FloatRect& viewportRectAtLastLayout() const { return m_viewportRectAtLastLayout; }
-    void setViewportRectAtLastLayout(const FloatRect& rect) { m_viewportRectAtLastLayout = rect; }
-
-    const FloatPoint& layerPositionAtLastLayout() const { return m_layerPositionAtLastLayout; }
-    void setLayerPositionAtLastLayout(const FloatPoint& point) { m_layerPositionAtLastLayout = point; }
-
-    bool operator==(const FixedPositionViewportConstraints& other) const
-    {
-        return m_alignmentOffset == other.m_alignmentOffset
-            && m_anchorEdges == other.m_anchorEdges
-            && m_viewportRectAtLastLayout == other.m_viewportRectAtLastLayout
-            && m_layerPositionAtLastLayout == other.m_layerPositionAtLastLayout;
-    }
-
-    bool operator!=(const FixedPositionViewportConstraints& other) const { return !(*this == other); }
-
-private:
-    ConstraintType constraintType() const override { return FixedPositionConstaint; }
-
-    FloatRect m_viewportRectAtLastLayout;
-    FloatPoint m_layerPositionAtLastLayout;
-};
-
-} // namespace blink
-
-#endif // ScrollingConstraints_h