Use ScrollAnchor in FrameView and PaintLayerScrollableArea.

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

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 135 matching lines @@
     , m_horizontalScrollbarLock(false)
     , m_verticalScrollbarLock(false)
     , m_scrollbarsAvoidingResizer(0)
     , m_scrollbarsSuppressed(false)
     , m_inUpdateScrollbars(false)
     , m_frameTimingRequestsDirty(true)
     , m_viewportIntersectionValid(false)
     , m_hiddenForThrottling(false)
     , m_crossOriginForThrottling(false)
     , m_isUpdatingAllLifecyclePhases(false)
+    , m_scrollAnchor(this)
 {
     ASSERT(m_frame);
     init();
 }
 
 PassRefPtrWillBeRawPtr<FrameView> FrameView::create(LocalFrame* frame)
 {
     RefPtrWillBeRawPtr<FrameView> view = adoptRefWillBeNoop(new FrameView(frame));
     view->show();
     return view.release();
@@ skipping 24 matching lines @@
 #if ENABLE(OILPAN)
     visitor->trace(m_frame);
     visitor->trace(m_fragmentAnchor);
     visitor->trace(m_scrollableAreas);
     visitor->trace(m_animatingScrollableAreas);
     visitor->trace(m_autoSizeInfo);
     visitor->trace(m_horizontalScrollbar);
     visitor->trace(m_verticalScrollbar);
     visitor->trace(m_children);
     visitor->trace(m_viewportScrollableArea);
+    visitor->trace(m_scrollAnchor);
 #endif
     Widget::trace(visitor);
     ScrollableArea::trace(visitor);
 }
 
 void FrameView::reset()
 {
     m_hasPendingLayout = false;
     m_doFullPaintInvalidation = false;
     m_layoutSchedulingEnabled = true;
@@ skipping 577 matching lines @@
 
     document->updateLayoutTreeIfNeeded();
     lifecycle().advanceTo(DocumentLifecycle::StyleClean);
 
     if (m_frame->isMainFrame() && !m_viewportScrollableArea) {
         ScrollableArea& visualViewport = m_frame->host()->visualViewport();
         ScrollableArea* layoutViewport = layoutViewportScrollableArea();
         ASSERT(layoutViewport);
         m_viewportScrollableArea = RootFrameViewport::create(visualViewport, *layoutViewport);
     }
+
+    if (scrollAnchoringEnabled())
+        m_scrollAnchor.save();
 }
 
 static inline void layoutFromRootObject(LayoutObject& root)
 {
     LayoutState layoutState(root);
     root.layout();
 }
 
 void FrameView::prepareLayoutAnalyzer()
 {
@@ skipping 715 matching lines @@
 void FrameView::setScrollPosition(const DoublePoint& scrollPoint, ScrollType scrollType, ScrollBehavior scrollBehavior)
 {
     DoublePoint newScrollPosition = clampScrollPosition(scrollPoint);
     if (newScrollPosition == scrollPositionDouble())
         return;
 
     if (scrollBehavior == ScrollBehaviorAuto)
         scrollBehavior = scrollBehaviorStyle();
 
     ScrollableArea::setScrollPosition(newScrollPosition, scrollType, scrollBehavior);
+
+    if (scrollAnchoringEnabled() && scrollType != AnchoringScroll)
+        m_scrollAnchor.clear();
 }
 
 void FrameView::didUpdateElasticOverscroll()
 {
     Page* page = frame().page();
     if (!page)
         return;
     FloatSize elasticOverscroll = page->chromeClient().elasticOverscroll();
     if (m_horizontalScrollbar) {
         float delta = elasticOverscroll.width() - m_horizontalScrollbar->elasticOverscroll();
@@ skipping 461 matching lines @@
     // Plugins could have torn down the page inside updateWidgetGeometries().
     if (!layoutView())
         return;
 
     scheduleUpdateWidgetsIfNecessary();
 
     if (ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator())
         scrollingCoordinator->notifyGeometryChanged();
 
     scrollToFragmentAnchor();
+    // TODO(skobes): Figure out interactions between scroll anchor, fragment anchor, and history restoration.
+    if (scrollAnchoringEnabled())
+        m_scrollAnchor.restore();
 
     sendResizeEventIfNeeded();
 }
 
 bool FrameView::wasViewportResized()
 {
     ASSERT(m_frame);
     LayoutView* layoutView = this->layoutView();
     if (!layoutView)
         return false;
@@ skipping 2027 matching lines @@
         return false;
     return m_hiddenForThrottling && m_crossOriginForThrottling;
 }
 
 LayoutBox& FrameView::boxForScrollControlPaintInvalidation() const
 {
     ASSERT(layoutView());
     return *layoutView();
 }
 
+bool FrameView::scrollAnchoringEnabled() const
+{
+    if (Settings* settings = frame().settings())
+        return settings->scrollAnchoringEnabled();
+    return false;
+}
+
 } // namespace blink