1 files changed, 29 insertions, 1 deletions
diff --git a/WebCore/platform/graphics/win/WKCACFLayer.cpp b/WebCore/platform/graphics/win/WKCACFLayer.cpp
index b5f3427..bbe5883 100644
--- a/WebCore/platform/graphics/win/WKCACFLayer.cpp
+++ b/WebCore/platform/graphics/win/WKCACFLayer.cpp
@@ -44,6 +44,24 @@ namespace WebCore {
 
 using namespace std;
 
+#ifndef NDEBUG
+void WKCACFLayer::internalCheckLayerConsistency()
+{
+    ASSERT(layer());
+    size_t n = sublayerCount();
+    for (size_t i = 0; i < n; ++i) {
+        // This will ASSERT in internalSublayerAtIndex if this entry doesn't have proper user data
+        WKCACFLayer* sublayer = internalSublayerAtIndex(i);
+
+        // Make sure we don't have any null entries in the list
+        ASSERT(sublayer);
+
+        // Make sure the each layer has a corresponding CACFLayer
+        ASSERT(sublayer->layer());
+    }
+}
+#endif
+
 static void displayCallback(CACFLayerRef layer, CGContextRef context)
 {
     ASSERT_ARG(layer, WKCACFLayer::layer(layer));
@@ -161,7 +179,14 @@ WKCACFLayer::~WKCACFLayer()
     // Our superlayer should be holding a reference to us, so there should be no way for us to be destroyed while we still have a superlayer.
     ASSERT(!superlayer());
 
+    // Get rid of the children so we don't have any dangling references around
+    removeAllSublayers();
+
+#ifndef NDEBUG
+    CACFLayerSetUserData(layer(), reinterpret_cast<void*>(0xDEADBEEF));
+#else
     CACFLayerSetUserData(layer(), 0);
+#endif
     CACFLayerSetDisplayCallback(layer(), 0);
 }
 
@@ -192,10 +217,11 @@ void WKCACFLayer::addSublayer(PassRefPtr<WKCACFLayer> sublayer)
 
 void WKCACFLayer::internalInsertSublayer(PassRefPtr<WKCACFLayer> sublayer, size_t index)
 {
-    index = min(index, sublayerCount());
+    index = min(index, sublayerCount() + 1);
     sublayer->removeFromSuperlayer();
     CACFLayerInsertSublayer(layer(), sublayer->layer(), index);
     setNeedsCommit();
+    checkLayerConsistency();
 }
 
 void WKCACFLayer::insertSublayerAboveLayer(PassRefPtr<WKCACFLayer> sublayer, const WKCACFLayer* reference)
@@ -268,12 +294,14 @@ void  WKCACFLayer::adoptSublayers(WKCACFLayer* source)
         sublayers.append(source->internalSublayerAtIndex(i));
 
     setSublayers(sublayers);
+    source->checkLayerConsistency();
 }
 
 void WKCACFLayer::removeFromSuperlayer()
 {
     WKCACFLayer* superlayer = this->superlayer();
     CACFLayerRemoveFromSuperlayer(layer());
+    checkLayerConsistency();
 
     if (superlayer)
         superlayer->setNeedsCommit();