Refactor MutatorHostClient from LayerTreeHost to LayerTree.

cc/layers/layer.h

 // Copyright 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_LAYERS_LAYER_H_
 #define CC_LAYERS_LAYER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 536 matching lines @@
 
   // When true, the layer is about to perform an update. Any commit requests
   // will be handled implicitly after the update completes.
   bool ignore_set_needs_commit_;
 
  private:
   friend class base::RefCounted<Layer>;
   friend class LayerSerializationTest;
   friend class LayerTreeHostCommon;
   friend class LayerTreeHost;
+  friend class LayerTree;
   friend class LayerInternalsForTest;
 
   // Interactions with attached animations.
   gfx::ScrollOffset ScrollOffsetForAnimation() const;
   void OnFilterAnimated(const FilterOperations& filters);
   void OnOpacityAnimated(float opacity);
   void OnTransformAnimated(const gfx::Transform& transform);
   void OnScrollOffsetAnimated(const gfx::ScrollOffset& scroll_offset);
   void OnTransformIsCurrentlyAnimatingChanged(bool is_animating);
   void OnTransformIsPotentiallyAnimatingChanged(bool is_animating);
@@ skipping 158 matching lines @@
   // These all act like draw properties, so don't need push properties.
   gfx::Rect visible_layer_rect_;
   size_t num_unclipped_descendants_;
 
   DISALLOW_COPY_AND_ASSIGN(Layer);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_LAYER_H_