Refactor MutatorHostClient from LayerTreeHost to LayerTree.

cc/trees/property_tree_builder.cc

Index: cc/trees/property_tree_builder.cc
diff --git a/cc/trees/property_tree_builder.cc b/cc/trees/property_tree_builder.cc
index 6fdde22ff7e7b85316e55815e110dd539a18d11e..feaaea8bbd7b7d85a76d31d2885627529df885f1 100644
--- a/cc/trees/property_tree_builder.cc
+++ b/cc/trees/property_tree_builder.cc
@@ -1437,7 +1437,7 @@ void PropertyTreeBuilder::BuildPropertyTrees(
       elastic_overscroll, page_scale_factor, device_scale_factor, viewport,
       device_transform, property_trees, color);
 #if DCHECK_IS_ON()
-  for (auto* layer : *root_layer->layer_tree_host())
+  for (auto* layer : *root_layer->GetLayerTree())
     CheckScrollAndClipPointersForLayer(layer);
 #endif
   property_trees->ResetCachedData();