Refactor MutatorHostClient from LayerTreeHost to LayerTree.

cc/trees/layer_tree_host_common.h

Index: cc/trees/layer_tree_host_common.h
diff --git a/cc/trees/layer_tree_host_common.h b/cc/trees/layer_tree_host_common.h
index 6867e942f368c033ac998957dad3de579c7f0453..8d9f4f804409c6a704108ee0a6abf22329f7f592 100644
--- a/cc/trees/layer_tree_host_common.h
+++ b/cc/trees/layer_tree_host_common.h
@@ -17,6 +17,7 @@
 #include "cc/layers/layer.h"
 #include "cc/layers/layer_collections.h"
 #include "cc/layers/layer_impl.h"
+#include "cc/trees/layer_tree.h"
 #include "cc/trees/layer_tree_host.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "cc/trees/property_tree.h"
@@ -132,7 +133,7 @@ class CC_EXPORT LayerTreeHostCommon {
       CalcDrawPropsImplInputsForTesting* inputs);
 
   template <typename Function>
-  static void CallFunctionForEveryLayer(LayerTreeHost* layer,
+  static void CallFunctionForEveryLayer(LayerTree* layer,
                                         const Function& function);
 
   template <typename Function>
@@ -179,7 +180,7 @@ struct CC_EXPORT ScrollAndScaleSet {
 };
 
 template <typename Function>
-void LayerTreeHostCommon::CallFunctionForEveryLayer(LayerTreeHost* host,
+void LayerTreeHostCommon::CallFunctionForEveryLayer(LayerTree* host,
                                                     const Function& function) {
   for (auto* layer : *host) {
     function(layer);