Add TransitionKeyframe class for CSS Transition refactor

third_party/WebKit/Source/core/animation/TransitionKeyframe.cpp

+// Copyright 2017 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 "core/animation/TransitionKeyframe.h"
+
+#include "core/animation/CompositorAnimations.h"
+#include "core/animation/InterpolationType.h"
+#include "core/animation/PairwiseInterpolationValue.h"
+#include "core/animation/TransitionInterpolation.h"
+
+namespace blink {
+
+void TransitionKeyframe::setCompositorValue(
+    RefPtr<AnimatableValue> compositorValue) {
+  DCHECK_EQ(
+      CompositorAnimations::isCompositableProperty(m_property.cssProperty()),
+      static_cast<bool>(compositorValue.get()));
+  m_compositorValue = std::move(compositorValue);
+}
+
+PropertyHandleSet TransitionKeyframe::properties() const {
+  PropertyHandleSet result;
+  result.insert(m_property);
+  return result;
+}
+
+PassRefPtr<Keyframe::PropertySpecificKeyframe>
+TransitionKeyframe::createPropertySpecificKeyframe(
+    const PropertyHandle& property) const {
+  DCHECK(property == m_property);
+  return PropertySpecificKeyframe::create(offset(), &easing(), composite(),
+                                          m_value->clone(), m_compositorValue);
+}
+
+PassRefPtr<Interpolation>
+TransitionKeyframe::PropertySpecificKeyframe::createInterpolation(
+    const PropertyHandle& property,
+    const Keyframe::PropertySpecificKeyframe& otherSuperClass) const {
+  const PropertySpecificKeyframe& other =
+      toTransitionPropertySpecificKeyframe(otherSuperClass);
+  DCHECK(m_value->type() == other.m_value->type());
+  return TransitionInterpolation::create(
+      property, m_value->type(), m_value->value().clone(),
+      other.m_value->value().clone(), m_compositorValue,
+      other.m_compositorValue);
+}
+
+}  // namespace blink