CC Animation: Use ElementId to attach CC animation players.

cc/trees/layer_tree_host.h

 // Copyright 2011 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_TREES_LAYER_TREE_HOST_H_
 #define CC_TREES_LAYER_TREE_HOST_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 329 matching lines @@
 
   void set_surface_id_namespace(uint32_t id_namespace);
   SurfaceSequence CreateSurfaceSequence();
 
   PropertyTrees* property_trees() { return &property_trees_; }
   bool needs_meta_info_recomputation() {
     return needs_meta_info_recomputation_;
   }
 
   Layer* LayerById(int id) const;
+  Layer* LayerForElementId(ElementId element_id) const;
+  Layer* ScrollLayerForElementId(ElementId element_id) const;
 
   void AddLayerShouldPushProperties(Layer* layer);
   void RemoveLayerShouldPushProperties(Layer* layer);
   std::unordered_set<Layer*>& LayersThatShouldPushProperties();
   bool LayerNeedsPushPropertiesForTesting(Layer* layer);
 
   void RegisterLayer(Layer* layer);
   void UnregisterLayer(Layer* layer);
+  void RegisterLayerForElementId(Layer* layer);
+  void UnregisterLayerForElementId(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,
@@ skipping 204 matching lines @@
 
   ImageSerializationProcessor* image_serialization_processor_;
 
   std::vector<std::unique_ptr<SwapPromise>> swap_promise_list_;
   std::set<SwapPromiseMonitor*> swap_promise_monitor_;
 
   PropertyTrees property_trees_;
 
   using LayerIdMap = std::unordered_map<int, Layer*>;
   LayerIdMap layer_id_map_;
+
+  struct ElementLayers {
+    // Transform, filter and opacity mutations apply to this layer.
+    Layer* main = nullptr;
+    // Scroll mutations apply to this layer.
+    Layer* scroll = nullptr;
+  };
+  using ElementIdToLayerMap = std::unordered_map<ElementId, ElementLayers>;
+  ElementIdToLayerMap element_id_to_layer_map_;
+
   // Set of layers that need to push properties.
   std::unordered_set<Layer*> layers_that_should_push_properties_;
 
   uint32_t surface_id_namespace_;
   uint32_t next_surface_sequence_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHost);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_H_