Use element id's for animations

cc/trees/property_tree.h

 // Copyright 2014 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_PROPERTY_TREE_H_
 #define CC_TREES_PROPERTY_TREE_H_
 
 #include <stddef.h>
 
 #include <memory>
 #include <unordered_map>
 #include <vector>
 
+#include "cc/animation/element_id.h"
 #include "cc/base/cc_export.h"
 #include "cc/base/synced_property.h"
 #include "ui/gfx/geometry/rect_f.h"
 #include "ui/gfx/geometry/scroll_offset.h"
 #include "ui/gfx/transform.h"
 
 namespace base {
 namespace trace_event {
 class TracedValue;
 }
@@ skipping 293 matching lines @@
   bool contains_non_fast_scrollable_region;
   gfx::Size scroll_clip_layer_bounds;
   gfx::Size bounds;
   bool max_scroll_offset_affected_by_page_scale;
   bool is_inner_viewport_scroll_layer;
   bool is_outer_viewport_scroll_layer;
   gfx::Vector2dF offset_to_transform_parent;
   bool should_flatten;
   bool user_scrollable_horizontal;
   bool user_scrollable_vertical;
-  int element_id;
+  ElementId element_id;
   int transform_id;
   // Number of drawn layers pointing to this node or any of its descendants.
   int num_drawn_descendants;
 
   bool operator==(const ScrollNodeData& other) const;
 
   void ToProtobuf(proto::TreeNode* proto) const;
   void FromProtobuf(const proto::TreeNode& proto);
   void AsValueInto(base::trace_event::TracedValue* value) const;
 };
@@ skipping 401 matching lines @@
 
  private:
   gfx::Vector2dF inner_viewport_container_bounds_delta_;
   gfx::Vector2dF outer_viewport_container_bounds_delta_;
   gfx::Vector2dF inner_viewport_scroll_bounds_delta_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_PROPERTY_TREE_H_