Compute style-determined compositing reasons during recalc style

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 1551 matching lines @@
         FrameView* frameView = m_renderView.frameView();
         m_containerLayer->setSize(frameView->unscaledVisibleContentSize());
     }
 }
 
 bool RenderLayerCompositor::has3DContent() const
 {
     return layerHas3DContent(rootRenderLayer());
 }
 
+void RenderLayerCompositor::updateStyleDeterminedCompositingReasons(RenderLayer* layer)
+{
+    CompositingReasons reasons = m_compositingReasonFinder.styleDeterminedReasons(layer->renderer());
+    layer->setCompositingReasons(reasons, CompositingReasonComboAllStyleDeterminedReasons);
+}
+
 void RenderLayerCompositor::updateDirectCompositingReasons(RenderLayer* layer)
 {
-    CompositingReasons layerReasons = layer->compositingReasons();
-
-    layerReasons &= ~CompositingReasonComboAllDirectReasons;
-    layerReasons |= m_compositingReasonFinder.directReasons(layer, &m_needsToRecomputeCompositingRequirements);
-    layer->setCompositingReasons(layerReasons);
+    CompositingReasons reasons = m_compositingReasonFinder.directReasons(layer, &m_needsToRecomputeCompositingRequirements);
+    layer->setCompositingReasons(reasons, CompositingReasonComboAllDirectReasons);
 }
 
 bool RenderLayerCompositor::needsOwnBacking(const RenderLayer* layer) const
 {
     if (!canBeComposited(layer))
         return false;
 
     // If squashing is disabled, then layers that would have been squashed should just be separately composited.
     bool needsOwnBackingForDisabledSquashing = !layerSquashingEnabled() && requiresSquashing(layer->compositingReasons());
 
@@ skipping 671 matching lines @@
     } else if (graphicsLayer == m_scrollLayer.get()) {
         name = "LocalFrame Scrolling Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace WebCore