Set geometry dirty bits on composited layer mappings when updating squashed layers.

Source/core/rendering/compositing/RenderLayerCompositor.cpp

 /*
  * Copyright (C) 2009, 2010 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
@@ skipping 638 matching lines @@
 }
 
 static IntPoint computeOffsetFromAbsolute(RenderLayer* layer)
 {
     TransformState transformState(TransformState::ApplyTransformDirection, FloatPoint());
     layer->renderer()->mapLocalToContainer(0, transformState, ApplyContainerFlip);
     transformState.flatten();
     return roundedIntPoint(transformState.lastPlanarPoint());
 }
 
 bool RenderLayerCompositor::updateSquashingAssignment(RenderLayer* layer, SquashingState& squashingState, const CompositingStateTransitionType compositedLayerUpdate)

[abarth-chromium, 2014/03/17 17:17:03]

What's the difference between these two updateSquashingLayerAssignment
functions?

 {
 
     // NOTE: In the future as we generalize this, the background of this layer may need to be assigned to a different backing than
     // the squashed RenderLayer's own primary contents. This would happen when we have a composited negative z-index element that needs
     // to paint on top of the background, but below the layer's main contents. For now, because we always composite layers
     // when they have a composited negative z-index child, such layers will never need squashing so it is not yet an issue.
     if (compositedLayerUpdate == PutInSquashingLayer) {
         // A layer that is squashed with other layers cannot have its own CompositedLayerMapping.
         ASSERT(!layer->hasCompositedLayerMapping());
         ASSERT(squashingState.hasMostRecentMapping);
@@ skipping 18 matching lines @@
         // FIXME: it seems premature to compute this before all compositing state has been updated?
         // This layer and all of its descendants have cached repaints rects that are relative to
         // the repaint container, so change when compositing changes; we need to update them here.
 
         // FIXME: what's up with parent()?
         if (layer->parent())
             layer->repainter().computeRepaintRectsIncludingDescendants();
 
         return true;
     } else if (compositedLayerUpdate == RemoveFromSquashingLayer) {
+        if (layer->groupedMapping())
+            layer->groupedMapping()->setNeedsGeometryUpdate();
         layer->setGroupedMapping(0);

[abarth-chromium, 2014/03/17 17:17:03]

Maybe this call to setNeedsGeometryUpdate should happen inside
setGroupedMapping.  Presumably every caller of setGroupedMapping needs this as
well.

[chrishtr, 2014/03/17 18:10:55]

Done.

 
         // This layer and all of its descendants have cached repaints rects that are relative to
         // the repaint container, so change when compositing changes; we need to update them here.
         layer->repainter().computeRepaintRectsIncludingDescendants();
 
         // If we need to repaint, do so now that we've removed it from a squashed layer
         repaintOnCompositingChange(layer);
 
         layer->setLostGroupedMapping(false);
         return true;
@@ skipping 1539 matching lines @@
     } else if (graphicsLayer == m_scrollLayer.get()) {
         name = "LocalFrame Scrolling Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace WebCore