Refactor MutatorHostClient from LayerTreeHost to LayerTree.

cc/trees/layer_tree_host.h

Index: cc/trees/layer_tree_host.h
diff --git a/cc/trees/layer_tree_host.h b/cc/trees/layer_tree_host.h
index 5ca13ecf20cfd2aee7fec1b9bc4b2afce1315d22..1b61733f83848c815cb1060b256de60b280d8dbe 100644
--- a/cc/trees/layer_tree_host.h
+++ b/cc/trees/layer_tree_host.h
@@ -43,7 +43,6 @@
 #include "cc/trees/layer_tree.h"
 #include "cc/trees/layer_tree_host_client.h"
 #include "cc/trees/layer_tree_settings.h"
-#include "cc/trees/mutator_host_client.h"
 #include "cc/trees/proxy.h"
 #include "cc/trees/swap_promise_monitor.h"
 #include "third_party/skia/include/core/SkColor.h"
@@ -83,7 +82,7 @@ namespace proto {
 class LayerTreeHost;
 }
 
-class CC_EXPORT LayerTreeHost : public MutatorHostClient {
+class CC_EXPORT LayerTreeHost {
  public:
   // TODO(sad): InitParams should be a movable type so that it can be
   // std::move()d to the Create* functions.
@@ -152,11 +151,6 @@ class CC_EXPORT LayerTreeHost : public MutatorHostClient {
   void DidCompleteSwapBuffers() { client_->DidCompleteSwapBuffers(); }
   bool UpdateLayers();
 
-  LayerListIterator<Layer> begin() const;
-  LayerListIterator<Layer> end() const;
-  LayerListReverseIterator<Layer> rbegin();
-  LayerListReverseIterator<Layer> rend();
-
   // Called when the compositor completed page scale animation.
   void DidCompletePageScaleAnimation();
 
@@ -296,7 +290,6 @@ class CC_EXPORT LayerTreeHost : public MutatorHostClient {
   TaskRunnerProvider* task_runner_provider() const {
     return task_runner_provider_.get();
   }
-  AnimationHost* animation_host() const;
 
   bool has_output_surface() const { return !!current_output_surface_; }
 
@@ -350,46 +343,6 @@ class CC_EXPORT LayerTreeHost : public MutatorHostClient {
 
   void SetLayerTreeMutator(std::unique_ptr<LayerTreeMutator> mutator);
 
-  Layer* LayerById(int id) const;
-
-  Layer* LayerByElementId(ElementId element_id) const;
-  void AddToElementMap(Layer* layer);
-  void RemoveFromElementMap(Layer* layer);
-
-  // MutatorHostClient implementation.
-  bool IsElementInList(ElementId element_id,
-                       ElementListType list_type) const override;
-  void SetMutatorsNeedCommit() override;
-  void SetMutatorsNeedRebuildPropertyTrees() override;
-  void SetElementFilterMutated(ElementId element_id,
-                               ElementListType list_type,
-                               const FilterOperations& filters) override;
-  void SetElementOpacityMutated(ElementId element_id,
-                                ElementListType list_type,
-                                float opacity) override;
-  void SetElementTransformMutated(ElementId element_id,
-                                  ElementListType list_type,
-                                  const gfx::Transform& transform) override;
-  void SetElementScrollOffsetMutated(
-      ElementId element_id,
-      ElementListType list_type,
-      const gfx::ScrollOffset& scroll_offset) override;
-  void ElementTransformIsAnimatingChanged(ElementId element_id,
-                                          ElementListType list_type,
-                                          AnimationChangeType change_type,
-                                          bool is_animating) override;
-  void ElementOpacityIsAnimatingChanged(ElementId element_id,
-                                        ElementListType list_type,
-                                        AnimationChangeType change_type,
-                                        bool is_animating) override;
-  void ElementFilterIsAnimatingChanged(ElementId element_id,
-                                       ElementListType list_type,
-                                       AnimationChangeType change_type,
-                                       bool is_animating) override;
-  void ScrollOffsetAnimationFinished() override {}
-  gfx::ScrollOffset GetScrollOffsetForAnimation(
-      ElementId element_id) const override;
-
   // Serializes the parts of this LayerTreeHost that is needed for a commit to a
   // protobuf message. Not all members are serialized as they are not helpful
   // for remote usage.
@@ -424,8 +377,8 @@ class CC_EXPORT LayerTreeHost : public MutatorHostClient {
     return client_picture_cache_ ? client_picture_cache_.get() : nullptr;
   }
 
-  LayerTree* GetLayerTree() { return &layer_tree_; }
-  const LayerTree* GetLayerTree() const { return &layer_tree_; }
+  LayerTree* GetLayerTree() { return layer_tree_.get(); }
+  const LayerTree* GetLayerTree() const { return layer_tree_.get(); }
 
  protected:
   LayerTreeHost(InitParams* params, CompositorMode mode);
@@ -591,15 +544,12 @@ class CC_EXPORT LayerTreeHost : public MutatorHostClient {
 
   PropertyTrees property_trees_;
 
-  using ElementLayersMap = std::unordered_map<ElementId, Layer*, ElementIdHash>;
-  ElementLayersMap element_layers_map_;
-
   uint32_t surface_client_id_;
   uint32_t next_surface_sequence_;
   uint32_t num_consecutive_frames_suitable_for_gpu_ = 0;
 
   // Layer tree that hold layers.
-  LayerTree layer_tree_;
+  std::unique_ptr<LayerTree> layer_tree_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHost);
 };