Web Animations: Split image slice interpolation out of LengthBoxStyleInterpolation

Source/core/animation/ImageSliceStyleInterpolation.h

+// 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 ImageSliceStyleInterpolation_h
+#define ImageSliceStyleInterpolation_h
+
+#include "core/animation/StyleInterpolation.h"
+
+namespace blink {
+
+class CSSBorderImageSliceValue;
+
+class ImageSliceStyleInterpolation : public StyleInterpolation {
+public:
+    static bool usesDefaultInterpolation(const CSSValue&, const CSSValue&);
+    static PassRefPtrWillBeRawPtr<ImageSliceStyleInterpolation> maybeCreate(const CSSValue&, const CSSValue&, CSSPropertyID);
+
+    virtual void apply(StyleResolverState&) const override;
+    DECLARE_VIRTUAL_TRACE();
+
+    // Image slices can have either percentages or numbers: http://dev.w3.org/csswg/css-backgrounds-3/#the-border-image-slice
+    struct Metadata {
+        bool isPercentage;
+        bool fill;
+        bool operator==(const Metadata& o) const { return isPercentage == o.isPercentage && fill == o.fill; }
+    };
+
+private:
+    ImageSliceStyleInterpolation(PassOwnPtrWillBeRawPtr<InterpolableValue> start, PassOwnPtrWillBeRawPtr<InterpolableValue> end, CSSPropertyID property, Metadata metadata)
+        : StyleInterpolation(start, end, property)
+        , m_metadata(metadata)
+    { }
+
+    Metadata m_metadata;
+};
+
+} // namespace blink
+
+#endif // ImageSliceStyleInterpolation_h