Add foundation for removing AnimatableValues from StyleInterpolation

Source/core/animation/AnimationType.h

Index: Source/core/animation/AnimationType.h
diff --git a/Source/core/animation/AnimationType.h b/Source/core/animation/AnimationType.h
new file mode 100644
index 0000000000000000000000000000000000000000..c7dabf9a264227bad7ae3d0e2373346acc189982
--- /dev/null
+++ b/Source/core/animation/AnimationType.h
@@ -0,0 +1,53 @@
+// Copyright 2015 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 AnimationType_h
+#define AnimationType_h
+
+#include "core/animation/InterpolableValue.h"
+#include "core/animation/NonInterpolableValue.h"
+#include "core/animation/PrimitiveInterpolation.h"
+#include "core/animation/StringKeyframe.h"
+#include "platform/heap/Handle.h"
+
+namespace blink {
+
+class StyleResolverState;
+
+// A singleton that:
+// - Converts from animation keyframe(s) to interpolation compatible representations: maybeConvertPairwise() and maybeConvertSingle()
+// - Applies interpolation compatible representations of values to a StyleResolverState: apply()
+class AnimationType {
+public:
+    CSSPropertyID property() const { return m_property; }
+
+    // Represents logic for determining whether a conversion decision is no longer valid given the current environment.
+    class ConversionChecker : public NoBaseWillBeGarbageCollectedFinalized<ConversionChecker> {
+    public:
+        virtual ~ConversionChecker() { }
+        virtual bool isValid(const StyleResolverState&) const = 0;
+        DEFINE_INLINE_VIRTUAL_TRACE() { }
+    };
+    using ConversionCheckers = WillBeHeapVector<OwnPtrWillBeMember<ConversionChecker>>;
+
+    virtual PassOwnPtrWillBeRawPtr<PairwisePrimitiveInterpolation> maybeConvertPairwise(const CSSPropertySpecificKeyframe& startKeyframe, const CSSPropertySpecificKeyframe& endKeyframe, const StyleResolverState*, ConversionCheckers&) const
+    {
+        return nullptr;
+    }
+
+    virtual PassOwnPtrWillBeRawPtr<FlipPrimitiveInterpolation::Side> maybeConvertSingle(const CSSPropertySpecificKeyframe&, const StyleResolverState*, ConversionCheckers&) const = 0;
+
+    virtual void apply(const InterpolableValue&, const NonInterpolableValue*, StyleResolverState&) const = 0;
+
+protected:
+    AnimationType(CSSPropertyID property)
+        : m_property(property)
+    { }
+
+    const CSSPropertyID m_property;
+};
+
+} // namespace blink
+
+#endif // AnimationType_h