Use ScrollAnchor in FrameView and PaintLayerScrollableArea.

third_party/WebKit/Source/core/frame/FrameView.h

 /*
    Copyright (C) 1997 Martin Jones (mjones@kde.org)
              (C) 1998 Waldo Bastian (bastian@kde.org)
              (C) 1998, 1999 Torben Weis (weis@kde.org)
              (C) 1999 Lars Knoll (knoll@kde.org)
              (C) 1999 Antti Koivisto (koivisto@kde.org)
    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 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
@@ skipping 13 matching lines @@
 
 #ifndef FrameView_h
 #define FrameView_h
 
 #include "core/CoreExport.h"
 #include "core/dom/DocumentLifecycle.h"
 #include "core/frame/FrameViewAutoSizeInfo.h"
 #include "core/frame/LayoutSubtreeRootList.h"
 #include "core/frame/RootFrameViewport.h"
 #include "core/layout/LayoutAnalyzer.h"
+#include "core/layout/ScrollAnchor.h"
 #include "core/paint/PaintInvalidationCapableScrollableArea.h"
 #include "core/paint/PaintPhase.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/Widget.h"
 #include "platform/geometry/IntRect.h"
 #include "platform/geometry/LayoutRect.h"
 #include "platform/graphics/Color.h"
 #include "platform/graphics/paint/ClipPaintPropertyNode.h"
 #include "platform/graphics/paint/TransformPaintPropertyNode.h"
 #include "platform/scroll/ScrollTypes.h"
@@ skipping 534 matching lines @@
 
     void setContentClip(PassRefPtr<ClipPaintPropertyNode> contentClip) { m_contentClip = contentClip; }
     ClipPaintPropertyNode* contentClip() const { return m_contentClip.get(); }
 
     // TODO(ojan): Merge this with IntersectionObserver once it lands.
     IntRect computeVisibleArea();
 
     // Viewport size that should be used for viewport units (i.e. 'vh'/'vw').
     FloatSize viewportSizeForViewportUnits() const;
 
+    ScrollAnchor& scrollAnchor() { return m_scrollAnchor; }
+
 protected:
     // Scroll the content via the compositor.
     bool scrollContentsFastPath(const IntSize& scrollDelta);
 
     // Scroll the content by invalidating everything.
     void scrollContentsSlowPath(const IntRect& updateRect);
 
     // These functions are used to create/destroy scrollbars.
     void setHasHorizontalScrollbar(bool);
     void setHasVerticalScrollbar(bool);
@@ skipping 151 matching lines @@
 
     void setNeedsUpdateViewportIntersection();
     void updateViewportIntersectionsForSubtree(LifeCycleUpdateOption);
     void updateViewportIntersectionIfNeeded();
     void notifyRenderThrottlingObservers();
 
     // PaintInvalidationCapableScrollableArea
     LayoutBox& boxForScrollControlPaintInvalidation() const override;
     LayoutScrollbarPart* resizer() const override { return nullptr; }
 
+    bool scrollAnchoringEnabled() const;
+
     LayoutSize m_size;
 
     typedef HashSet<RefPtr<LayoutEmbeddedObject>> EmbeddedObjectSet;
     EmbeddedObjectSet m_partUpdateSet;
 
     // FIXME: These are just "children" of the FrameView and should be RefPtrWillBeMember<Widget> instead.
     HashSet<RefPtr<LayoutPart>> m_parts;
 
     // The RefPtr cycle between LocalFrame and FrameView is broken
     // when a LocalFrame is detached by LocalFrame::detach().
@@ skipping 120 matching lines @@
     // [ preTranslation ]               The offset from Widget::frameRect. Establishes viewport.
     //     +---[ scrollTranslation ]    Frame scrolling.
     // TODO(trchen): These will not be needed once settings->rootLayerScrolls() is enabled.
     RefPtr<TransformPaintPropertyNode> m_preTranslation;
     RefPtr<TransformPaintPropertyNode> m_scrollTranslation;
     // The content clip clips the document (= LayoutView) but not the scrollbars.
     // TODO(trchen): This will not be needed once settings->rootLayerScrolls() is enabled.
     RefPtr<ClipPaintPropertyNode> m_contentClip;
 
     bool m_isUpdatingAllLifecyclePhases;
+    ScrollAnchor m_scrollAnchor;
 };
 
 inline void FrameView::incrementVisuallyNonEmptyCharacterCount(unsigned count)
 {
     if (m_isVisuallyNonEmpty)
         return;
     m_visuallyNonEmptyCharacterCount += count;
     // Use a threshold value to prevent very small amounts of visible content from triggering didMeaningfulLayout.
     // The first few hundred characters rarely contain the interesting content of the page.
     static const unsigned visualCharacterThreshold = 200;
@@ skipping 11 matching lines @@
     if (m_visuallyNonEmptyPixelCount > visualPixelThreshold)
         setIsVisuallyNonEmpty();
 }
 
 DEFINE_TYPE_CASTS(FrameView, Widget, widget, widget->isFrameView(), widget.isFrameView());
 DEFINE_TYPE_CASTS(FrameView, ScrollableArea, scrollableArea, scrollableArea->isFrameView(), scrollableArea.isFrameView());
 
 } // namespace blink
 
 #endif // FrameView_h