Tie scroll anchoring adjustments to frame lifecycle instead of layout.

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 206 matching lines @@
   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);
+  visitor->trace(m_anchoringAdjustmentQueue);
   Widget::trace(visitor);
   ScrollableArea::trace(visitor);
 }
 
 void FrameView::reset() {
   m_hasPendingLayout = false;
   m_layoutSchedulingEnabled = true;
   m_inSynchronousPostLayout = false;
   m_layoutCount = 0;
   m_nestedLayoutCount = 0;
@@ skipping 602 matching lines @@
        document->styleResolver()->mediaQueryAffectedByDeviceChange())) {
     document->mediaQueryAffectingValueChanged();
   } else if (wasResized) {
     document->evaluateMediaQueryList();
   }
 
   document->updateStyleAndLayoutTree();
   lifecycle().advanceTo(DocumentLifecycle::StyleClean);
 
   if (shouldPerformScrollAnchoring())
-    m_scrollAnchor.save();
+    m_scrollAnchor.notifyBeforeLayout();
 }
 
 bool FrameView::shouldPerformScrollAnchoring() const {
   return RuntimeEnabledFeatures::scrollAnchoringEnabled() &&
          !RuntimeEnabledFeatures::rootLayerScrollingEnabled() &&
          m_scrollAnchor.hasScroller() &&
          layoutBox()->style()->overflowAnchor() != AnchorNone;
 }
 
 static inline void layoutFromRootObject(LayoutObject& root) {
@@ skipping 1355 matching lines @@
   // Plugins could have torn down the page inside updateWidgetGeometries().
   if (layoutViewItem().isNull())
     return;
 
   scheduleUpdateWidgetsIfNecessary();
 
   if (ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator())
     scrollingCoordinator->notifyGeometryChanged();
 
   scrollToFragmentAnchor();
-  // TODO(skobes): Figure out interactions between scroll anchor, fragment
-  // anchor, and history restoration.
-  if (shouldPerformScrollAnchoring())
-    m_scrollAnchor.restore();
-
   sendResizeEventIfNeeded();
 }
 
 bool FrameView::wasViewportResized() {
   ASSERT(m_frame);
   LayoutViewItem layoutViewItem = this->layoutViewItem();
   if (layoutViewItem.isNull())
     return false;
   ASSERT(layoutViewItem.style());
   return (layoutSize(IncludeScrollbars) != m_lastViewportSize ||
@@ skipping 406 matching lines @@
   }
 
   updateStyleAndLayoutIfNeededRecursive();
   DCHECK(lifecycle().state() >= DocumentLifecycle::LayoutClean);
 
   if (targetState == DocumentLifecycle::LayoutClean) {
     updateViewportIntersectionsForSubtree(targetState);
     return;
   }
 
+  forAllNonThrottledFrameViews([](FrameView& frameView) {

[szager1, 2016/10/13 17:54:49]

Shouldn't this happen before updateViewportIntersectionsForSubtree?

[skobes, 2016/10/13 18:00:31]

It does.  For targetState > LayoutClean, the call to
updateViewportIntersectionsForSubtree occurs at the end of the function.

For targetState <= LayoutClean we do not perform the scroll anchoring
adjustments.

[szager1, 2016/10/13 18:50:56]

Ah, I see, thanks.

+    frameView.performScrollAnchoringAdjustments();
+  });
+
   if (targetState == DocumentLifecycle::PaintClean) {
     forAllNonThrottledFrameViews(
         [](FrameView& frameView) { frameView.notifyResizeObservers(); });
   }
 
   if (LayoutViewItem view = layoutViewItem()) {
     forAllNonThrottledFrameViews([](FrameView& frameView) {
       frameView.checkDoesNotNeedLayout();
       frameView.m_allowsLayoutInvalidationAfterLayoutClean = false;
     });
@@ skipping 47 matching lines @@
 
     forAllNonThrottledFrameViews([](FrameView& frameView) {
       frameView.checkDoesNotNeedLayout();
       frameView.m_allowsLayoutInvalidationAfterLayoutClean = true;
     });
   }
 
   updateViewportIntersectionsForSubtree(targetState);
 }
 
+void FrameView::enqueueScrollAnchoringAdjustment(
+    ScrollableArea* scrollableArea) {
+  m_anchoringAdjustmentQueue.add(scrollableArea);
+}
+
+void FrameView::performScrollAnchoringAdjustments() {
+  for (WeakMember<ScrollableArea>& scroller : m_anchoringAdjustmentQueue) {
+    if (scroller)
+      scroller->scrollAnchor()->adjust();
+  }
+  m_anchoringAdjustmentQueue.clear();
+}
+
 void FrameView::updatePaintProperties() {
   TRACE_EVENT0("blink", "FrameView::updatePaintProperties");
 
   if (!m_paintController)
     m_paintController = PaintController::create();
 
   forAllNonThrottledFrameViews([](FrameView& frameView) {
     frameView.lifecycle().advanceTo(DocumentLifecycle::InPrePaint);
   });
 
@@ skipping 870 matching lines @@
     cache->handleScrollPositionChanged(this);
 
   frame().loader().saveScrollState();
   didChangeScrollOffset();
 
   if (scrollType == CompositorScroll && m_frame->isMainFrame()) {
     if (DocumentLoader* documentLoader = m_frame->loader().documentLoader())
       documentLoader->initialScrollState().wasScrolledByUser = true;
   }
 
-  if (scrollType != AnchoringScroll)
+  if (scrollType != AnchoringScroll && scrollType != ClampingScroll)
     clearScrollAnchor();
 }
 
 void FrameView::didChangeScrollOffset() {
   frame().loader().client()->didChangeScrollOffset();
   if (frame().isMainFrame())
     frame().host()->chromeClient().mainFrameScrollOffsetChanged();
 }
 
 void FrameView::clearScrollAnchor() {
@@ skipping 207 matching lines @@
     frameRectsChanged();
     positionScrollbarLayers();
     updateScrollCorner();
   }
 
   adjustScrollOffsetFromUpdateScrollbars();
 }
 
 void FrameView::adjustScrollOffsetFromUpdateScrollbars() {
   ScrollOffset clamped = clampScrollOffset(scrollOffset());
-  // Restore before clamping because clamping clears the scroll anchor.
-  // TODO(ymalik): This same logic exists in PaintLayerScrollableArea.
-  // Remove when root-layer-scrolls is enabled.
-  if (clamped != scrollOffset() && shouldPerformScrollAnchoring()) {
-    m_scrollAnchor.restore();
-    clamped = clampScrollOffset(scrollOffset());
-  }
   if (clamped != scrollOffset() || scrollOriginChanged()) {
-    ScrollableArea::setScrollOffset(clamped, ProgrammaticScroll);
+    ScrollableArea::setScrollOffset(clamped, ClampingScroll);
     resetScrollOriginChanged();
   }
 }
 
 void FrameView::scrollContentsIfNeeded() {
   if (m_pendingScrollDelta.isZero())
     return;
   ScrollOffset scrollDelta = m_pendingScrollDelta;
   m_pendingScrollDelta = ScrollOffset();
   // FIXME: Change scrollContents() to take DoubleSize. crbug.com/414283.
@@ skipping 613 matching lines @@
 }
 
 bool FrameView::canThrottleRendering() const {
   if (!RuntimeEnabledFeatures::renderingPipelineThrottlingEnabled())
     return false;
   return m_subtreeThrottled ||
          (m_hiddenForThrottling && m_crossOriginForThrottling);
 }
 
 }  // namespace blink