Revert of Use element id's for animations

cc/layers/layer_impl.h

Index: cc/layers/layer_impl.h
diff --git a/cc/layers/layer_impl.h b/cc/layers/layer_impl.h
index 5befbbcefbb707d639a9a414e1e83dbe13a1596d..8a79d12d1139042c9caafb0df5405ca6ebddc013 100644
--- a/cc/layers/layer_impl.h
+++ b/cc/layers/layer_impl.h
@@ -18,7 +18,6 @@
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/values.h"
-#include "cc/animation/element_id.h"
 #include "cc/animation/target_property.h"
 #include "cc/base/cc_export.h"
 #include "cc/base/region.h"
@@ -236,8 +235,8 @@
   bool OpacityIsAnimating() const;
   bool HasPotentiallyRunningOpacityAnimation() const;
 
-  void SetElementId(ElementId element_id);
-  ElementId element_id() const { return element_id_; }
+  void SetElementId(uint64_t element_id);
+  uint64_t element_id() const { return element_id_; }
 
   void SetMutableProperties(uint32_t properties);
   uint32_t mutable_properties() const { return mutable_properties_; }
@@ -620,7 +619,7 @@
   DrawMode current_draw_mode_;
 
  private:
-  ElementId element_id_;
+  uint64_t element_id_;
   uint32_t mutable_properties_;
   // Rect indicating what was repainted/updated during update.
   // Note that plugin layers bypass this and leave it empty.