cc: Clear entries from animations maps only when main thread wins

cc/layers/layer_impl.cc

Index: cc/layers/layer_impl.cc
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index 1ad29f0a51f300aed28b34fbe6e220075691ab15..08e5b430af30cdfc50b2fea1415e81ef470196c4 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -587,6 +587,15 @@ void LayerImpl::UpdatePropertyTreeForScrollingAndAnimationIfNeeded() {
     UpdatePropertyTreeScrollOffset();
 
   if (HasAnyAnimationTargetingProperty(TargetProperty::TRANSFORM)) {
+#if DCHECK_IS_ON()
+    PropertyTrees* property_trees = layer_tree_impl()->property_trees();
+    if (property_trees->IsInIdToIndexMap(PropertyTrees::TreeType::TRANSFORM,
+                                         id())) {
+      TransformNode* node = property_trees->transform_tree.Node(
+          property_trees->transform_id_to_index_map[id()]);
+      DCHECK(transform_.ApproximatelyEqual(node->data.local));
+    }
+#endif
     UpdatePropertyTreeTransformIsAnimated(
         HasPotentiallyRunningTransformAnimation());
   }