Merge 98060 - Hidden composited iframes cause infinite loop

Source/WebCore/rendering/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 77 matching lines @@
 #ifndef NDEBUG
     int m_depth;
 #endif
 };
 
 RenderLayerCompositor::RenderLayerCompositor(RenderView* renderView)
     : m_renderView(renderView)
     , m_updateCompositingLayersTimer(this, &RenderLayerCompositor::updateCompositingLayersTimerFired)
     , m_hasAcceleratedCompositing(true)
     , m_compositingTriggers(static_cast<ChromeClient::CompositingTriggerFlags>(ChromeClient::AllTriggers))
+    , m_compositedLayerCount(0)
     , m_showDebugBorders(false)
     , m_showRepaintCounter(false)
     , m_compositingConsultsOverlap(true)
     , m_compositingDependsOnGeometry(false)
     , m_compositing(false)
     , m_compositingLayersNeedRebuild(false)
     , m_flushingLayers(false)
     , m_forceCompositingMode(false)
     , m_rootLayerAttachment(RootLayerUnattached)
 #if PROFILE_LAYER_REBUILD
@@ skipping 126 matching lines @@
 {
     if (!m_updateCompositingLayersTimer.isActive())
         m_updateCompositingLayersTimer.startOneShot(0);
 }
 
 void RenderLayerCompositor::updateCompositingLayersTimerFired(Timer<RenderLayerCompositor>*)
 {
     updateCompositingLayers();
 }
 
+bool RenderLayerCompositor::hasAnyAdditionalCompositedLayers(const RenderLayer* rootLayer) const
+{
+    return m_compositedLayerCount > rootLayer->isComposited();
+}
+
 void RenderLayerCompositor::updateCompositingLayers(CompositingUpdateType updateType, RenderLayer* updateRoot)
 {
     m_updateCompositingLayersTimer.stop();
 
     if (m_forceCompositingMode && !m_compositing)
         enableCompositingMode(true);
 
     if (!m_compositingDependsOnGeometry && !m_compositing)
         return;
 
@@ skipping 44 matching lines @@
     }
 
     if (needHierarchyUpdate) {
         // Update the hierarchy of the compositing layers.
         CompositingState compState(updateRoot);
         Vector<GraphicsLayer*> childList;
         rebuildCompositingLayerTree(updateRoot, compState, childList);
 
         // Host the document layer in the RenderView's root layer.
         if (updateRoot == rootRenderLayer()) {
-            if (childList.isEmpty())
+            // Even when childList is empty, don't drop out of compositing mode if there are
+            // composited layers that we didn't hit in our traversal (e.g. because of visibility:hidden).
+            if (childList.isEmpty() && !hasAnyAdditionalCompositedLayers(updateRoot))
                 destroyRootLayer();
             else
                 m_rootContentLayer->setChildren(childList);
         }
     } else if (needGeometryUpdate) {
         // We just need to do a geometry update. This is only used for position:fixed scrolling;
         // most of the time, geometry is updated via RenderLayer::styleChanged().
         updateLayerTreeGeometry(updateRoot);
     }
     
@@ skipping 444 matching lines @@
 
     // setHasCompositingDescendant() may have changed the answer to needsToBeComposited() when clipping,
     // so test that again.
     if (!willBeComposited && canBeComposited(layer) && clipsCompositingDescendants(layer)) {
         if (overlapMap)
             addToOverlapMapRecursive(*overlapMap, layer);
         willBeComposited = true;
     }
 
     // If we're back at the root, and no other layers need to be composited, and the root layer itself doesn't need
-    // to be composited, then we can drop out of compositing mode altogether.
-    if (layer->isRootLayer() && !childState.m_subtreeIsCompositing && !requiresCompositingLayer(layer) && !m_forceCompositingMode) {
+    // to be composited, then we can drop out of compositing mode altogether. However, don't drop out of compositing mode
+    // if there are composited layers that we didn't hit in our traversal (e.g. because of visibility:hidden).
+    if (layer->isRootLayer() && !childState.m_subtreeIsCompositing && !requiresCompositingLayer(layer) && !m_forceCompositingMode && !hasAnyAdditionalCompositedLayers(layer)) {
         enableCompositingMode(false);
         willBeComposited = false;
     }
     
     // If the layer is going into compositing mode, repaint its old location.
     ASSERT(willBeComposited == needsToBeComposited(layer));
     if (!layer->isComposited() && willBeComposited)
         repaintOnCompositingChange(layer);
 
     // Update backing now, so that we can use isComposited() reliably during tree traversal in rebuildCompositingLayerTree().
@@ skipping 1117 matching lines @@
     if (!viewLayer->isComposited())
         return;
 
     if (GraphicsLayer* rootLayer = viewLayer->backing()->graphicsLayer())
         rootLayer->noteDeviceOrPageScaleFactorChangedIncludingDescendants();
 }
 
 } // namespace WebCore
 
 #endif // USE(ACCELERATED_COMPOSITING)