Remove usesCompositedScrolling

sky/engine/core/rendering/RenderLayerScrollableArea.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 288 matching lines @@
 
     if (box().view()->compositor()->inCompositingMode()) {
         // Hits in virtual/gpu/fast/canvas/canvas-scroll-path-into-view.html.
         DisableCompositingQueryAsserts disabler;
         bool onlyScrolledCompositedLayers = scrollsOverflow()
             && !layer()->hasVisibleNonLayerContent()
             && !layer()->hasNonCompositedChild()
             && !layer()->hasBlockSelectionGapBounds()
             && box().style()->backgroundLayers().attachment() != LocalBackgroundAttachment;
 
-        if (usesCompositedScrolling() || onlyScrolledCompositedLayers)
+        if (onlyScrolledCompositedLayers)

[rafaelw, 2014/11/07 19:41:48]

Given the name of this bool, I might guess that this entire block should go away
and we should always just require paint invalidation below, but I can't tell if
that's safe.

[abarth-chromium, 2014/11/07 19:44:23]

That sounds right.

             requiresPaintInvalidation = false;
     }
 
     // Just schedule a full paint invalidation of our object.
     if (requiresPaintInvalidation) {
         // For querying RenderLayer::compositingState()
         // This code appears correct, since scrolling outside of layout happens during activities that do not dirty compositing state.
         DisableCompositingQueryAsserts disabler;
         if (box().frameView()->isInPerformLayout())
             box().setShouldDoFullPaintInvalidation(true);
@@ skipping 61 matching lines @@
     return box().frame() ? box().frame()->eventHandler().lastKnownMousePosition() : IntPoint();
 }
 
 IntRect RenderLayerScrollableArea::scrollableAreaBoundingBox() const
 {
     return box().absoluteBoundingBoxRect();
 }
 
 bool RenderLayerScrollableArea::userInputScrollable(ScrollbarOrientation orientation) const
 {
-    if (box().isIntristicallyScrollable(orientation))
-        return true;
-
     EOverflow overflowStyle = (orientation == HorizontalScrollbar) ?
         box().style()->overflowX() : box().style()->overflowY();
     return (overflowStyle == OSCROLL || overflowStyle == OAUTO || overflowStyle == OOVERLAY);
 }
 
 bool RenderLayerScrollableArea::shouldPlaceVerticalScrollbarOnLeft() const
 {
     return box().style()->shouldPlaceBlockDirectionScrollbarOnLogicalLeft();
 }
 
@@ skipping 499 matching lines @@
     if (m_scrollsOverflow)
         frameView->addScrollableArea(this);
     else
         frameView->removeScrollableArea(this);
 }
 
 void RenderLayerScrollableArea::updateCompositingLayersAfterScroll()
 {
     RenderLayerCompositor* compositor = box().view()->compositor();
     if (compositor->inCompositingMode()) {
-        if (usesCompositedScrolling()) {
-            DisableCompositingQueryAsserts disabler;
-            ASSERT(layer()->hasCompositedLayerMapping());
-            layer()->compositedLayerMapping()->setNeedsGraphicsLayerUpdate(GraphicsLayerUpdateSubtree);
-            compositor->setNeedsCompositingUpdate(CompositingUpdateAfterGeometryChange);
-        } else {
-            layer()->setNeedsCompositingInputsUpdate();
-        }
+        layer()->setNeedsCompositingInputsUpdate();
     }
 }
 
-bool RenderLayerScrollableArea::usesCompositedScrolling() const
-{
-    // Scroll form controls on the main thread so they exhibit correct touch scroll event bubbling
-    if (box().isIntristicallyScrollable(VerticalScrollbar) || box().isIntristicallyScrollable(HorizontalScrollbar))
-        return false;
-
-    // See https://codereview.chromium.org/176633003/ for the tests that fail without this disabler.
-    DisableCompositingQueryAsserts disabler;
-    return layer()->hasCompositedLayerMapping() && layer()->compositedLayerMapping()->scrollingLayer();
-}
-
 static bool layerNeedsCompositedScrolling(const RenderLayer* layer)
 {
     return layer->scrollsOverflow()
         && layer->compositor()->preferCompositingToLCDTextEnabled()
         && !layer->hasDescendantWithClipPath()
         && !layer->hasAncestorWithClipPath();
 }
 
 void RenderLayerScrollableArea::updateNeedsCompositedScrolling()
 {
     const bool needsCompositedScrolling = layerNeedsCompositedScrolling(layer());
     if (static_cast<bool>(m_needsCompositedScrolling) != needsCompositedScrolling) {
         m_needsCompositedScrolling = needsCompositedScrolling;
         layer()->didUpdateNeedsCompositedScrolling();
     }
 }
 
 void RenderLayerScrollableArea::setTopmostScrollChild(RenderLayer* scrollChild)
 {
     // We only want to track the topmost scroll child for scrollable areas with
     // overlay scrollbars.
     if (!hasOverlayScrollbars())
         return;
     m_nextTopmostScrollChild = scrollChild;
 }
 
 } // namespace blink