Revert of Use element id's for animations

cc/animation/element_id.cc

Index: cc/animation/element_id.cc
diff --git a/cc/animation/element_id.cc b/cc/animation/element_id.cc
deleted file mode 100644
index 242cd32e621e37a9fb844d567dbc0f0a1c026410..0000000000000000000000000000000000000000
--- a/cc/animation/element_id.cc
+++ /dev/null
@@ -1,67 +0,0 @@
-// Copyright 2016 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.
-
-#include "cc/animation/element_id.h"
-
-#include <limits>
-#include <ostream>
-
-#include "base/trace_event/trace_event_argument.h"
-#include "base/values.h"
-#include "cc/proto/element_id.pb.h"
-
-namespace cc {
-
-bool ElementId::operator==(const ElementId& o) const {
-  return primaryId == o.primaryId && secondaryId == o.secondaryId;
-}
-
-bool ElementId::operator!=(const ElementId& o) const {
-  return !(*this == o);
-}
-
-bool ElementId::operator<(const ElementId& o) const {
-  return std::tie(primaryId, secondaryId) <
-         std::tie(o.primaryId, o.secondaryId);
-}
-
-ElementId::operator bool() const {
-  return !!primaryId;
-}
-
-ElementId LayerIdToElementIdForTesting(int layer_id) {
-  return ElementId(std::numeric_limits<int>::max() - layer_id, 0);
-}
-
-void ElementId::AddToTracedValue(base::trace_event::TracedValue* res) const {
-  res->SetInteger("primaryId", primaryId);
-  res->SetInteger("secondaryId", secondaryId);
-}
-
-std::unique_ptr<base::Value> ElementId::AsValue() const {
-  std::unique_ptr<base::DictionaryValue> res(new base::DictionaryValue());
-  res->SetInteger("primaryId", primaryId);
-  res->SetInteger("secondaryId", secondaryId);
-  return std::move(res);
-}
-
-void ElementId::ToProtobuf(proto::ElementId* proto) const {
-  proto->set_primary_id(primaryId);
-  proto->set_secondary_id(secondaryId);
-}
-
-void ElementId::FromProtobuf(const proto::ElementId& proto) {
-  primaryId = proto.primary_id();
-  secondaryId = proto.secondary_id();
-}
-
-size_t ElementIdHash::operator()(ElementId key) const {
-  return base::HashInts(key.primaryId, key.secondaryId);
-}
-
-std::ostream& operator<<(std::ostream& out, const ElementId& id) {
-  return out << "(" << id.primaryId << ", " << id.secondaryId << ")";
-}
-
-}  // namespace cc