Removing a RenderLayer's CLM should trigger a repaint

Source/core/rendering/compositing/RenderLayerCompositor.cpp

Index: Source/core/rendering/compositing/RenderLayerCompositor.cpp
diff --git a/Source/core/rendering/compositing/RenderLayerCompositor.cpp b/Source/core/rendering/compositing/RenderLayerCompositor.cpp
index 81603f801f981f1f2d05c5322fefc8b5cb3b13c7..6233c5d66ea752ae4e554dce5ac58f73560d6328 100644
--- a/Source/core/rendering/compositing/RenderLayerCompositor.cpp
+++ b/Source/core/rendering/compositing/RenderLayerCompositor.cpp
@@ -480,8 +480,19 @@ bool RenderLayerCompositor::updateLayerIfViewportConstrained(RenderLayer* layer)
 // See crbug.com/383191 for a list of tests that fail if this method is removed.
 void RenderLayerCompositor::applyUpdateLayerCompositingStateChickenEggHacks(RenderLayer* layer, CompositingStateTransitionType compositedLayerUpdate)
 {
-    if (compositedLayerUpdate != NoCompositingStateChange)
-        allocateOrClearCompositedLayerMapping(layer, compositedLayerUpdate);
+    if (compositedLayerUpdate != NoCompositingStateChange) {
+        bool compositedLayerMappingChanged = allocateOrClearCompositedLayerMapping(layer, compositedLayerUpdate);
+        if (compositedLayerMappingChanged) {
+            // Repaint rects can only be computed for layers that have already been attached to the
+            // render tree, but a chicken-egg compositing update can happen before |layer| gets
+            // attached. Since newly-created renderers don't get parented until they are attached
+            // (see RenderTreeBuilder::createRendererForElementIfNeeded), we can check for attachment
+            // by checking for a parent.
+            if (layer->parent())
+                layer->repainter().computeRepaintRectsIncludingNonCompositingDescendants();
+            repaintOnCompositingChange(layer);
+        }
+    }
 }
 
 void RenderLayerCompositor::updateLayerCompositingState(RenderLayer* layer, UpdateLayerCompositingStateOptions options)