Get rid of slow repaint objects and main thread scrolling reasons.

sky/engine/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 299 matching lines @@
         // If this layer was previously squashed, we need to remove its reference to a groupedMapping right away, so
         // that computing paint invalidation rects will know the layer's correct compositingState.
         // FIXME: do we need to also remove the layer from it's location in the squashing list of its groupedMapping?
         // Need to create a test where a squashed layer pops into compositing. And also to cover all other
         // sorts of compositingState transitions.
         layer->setLostGroupedMapping(false);
         layer->setGroupedMapping(0);
 
         layer->ensureCompositedLayerMapping();
         compositedLayerMappingChanged = true;
-
-        // At this time, the ScrollingCooridnator only supports the top-level frame.
-        if (layer->isRootLayer()) {
-            if (ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator())
-                scrollingCoordinator->frameViewRootLayerDidChange(m_renderView.frameView());
-        }
         break;
     case RemoveOwnCompositedLayerMapping:
     // PutInSquashingLayer means you might have to remove the composited layer mapping first.
     case PutInSquashingLayer:
         if (layer->hasCompositedLayerMapping()) {
             layer->clearCompositedLayerMapping();
             compositedLayerMappingChanged = true;
         }
 
         break;
     case RemoveFromSquashingLayer:
     case NoCompositingStateChange:
         // Do nothing.
         break;
     }
 
     if (layer->hasCompositedLayerMapping() && layer->compositedLayerMapping()->updateRequiresOwnBackingStoreForIntrinsicReasons())
         compositedLayerMappingChanged = true;
 
     if (compositedLayerMappingChanged && layer->renderer()->isRenderPart()) {
         RenderLayerCompositor* innerCompositor = frameContentsCompositor(toRenderPart(layer->renderer()));
         if (innerCompositor && innerCompositor->staleInCompositingMode())
             innerCompositor->updateRootLayerAttachment();
     }
 
     if (compositedLayerMappingChanged)
         layer->clipper().clearClipRectsIncludingDescendants(PaintingClipRects);
 
-    // If a fixed position layer gained/lost a compositedLayerMapping or the reason not compositing it changed,
-    // the scrolling coordinator needs to recalculate whether it can do fast scrolling.
-    if (compositedLayerMappingChanged) {
-        if (ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator())
-            scrollingCoordinator->frameViewFixedObjectsDidChange(m_renderView.frameView());
-    }
-
     return compositedLayerMappingChanged;
 }
 
 void RenderLayerCompositor::paintInvalidationOnCompositingChange(RenderLayer* layer)
 {
     // If the renderer is not attached yet, no need to issue paint invalidations.
     if (layer->renderer() != &m_renderView && !layer->renderer()->parent())
         return;
 
     // For querying RenderLayer::compositingState()
@@ skipping 566 matching lines @@
     } else if (graphicsLayer == m_scrollLayer.get()) {
         name = "LocalFrame Scrolling Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace blink