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 69124f52115bfd792716627d90f466deb97e74f4..7cfc6c3895fa51bc8d85a17a7783a30c24f9bd73 100644
--- a/cc/trees/property_tree_builder.cc
+++ b/cc/trees/property_tree_builder.cc
@@ -18,7 +18,6 @@
 #include "cc/trees/clip_node.h"
 #include "cc/trees/draw_property_utils.h"
 #include "cc/trees/effect_node.h"
-#include "cc/trees/layer_tree_host.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "cc/trees/scroll_node.h"
 #include "cc/trees/transform_node.h"
@@ -27,8 +26,6 @@
 
 namespace cc {
 
-class LayerTreeHost;
-
 namespace {
 
 static const int kInvalidPropertyTreeNodeId = -1;
@@ -1435,7 +1432,7 @@ 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();