Make InterpolationEnvironment virutal

third_party/WebKit/Source/core/animation/SVGInterpolationEnvironment.h

+// 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.
+
+#ifndef SVGInterpolationEnvironment_h
+#define SVGInterpolationEnvironment_h
+
+#include "core/animation/InterpolationEnvironment.h"
+#include "platform/wtf/Assertions.h"
+
+namespace blink {
+
+class SVGPropertyBase;
+class SVGElement;
+
+class SVGInterpolationEnvironment : public InterpolationEnvironment {
+ public:
+  explicit SVGInterpolationEnvironment(const InterpolationTypesMap& map,
+                                       SVGElement& svg_element,
+                                       const SVGPropertyBase& svg_base_value)
+      : InterpolationEnvironment(map),
+        svg_element_(&svg_element),
+        svg_base_value_(&svg_base_value) {}
+
+  bool IsSVG() const final { return true; }
+
+  SVGElement& SvgElement() {
+    DCHECK(svg_element_);
+    return *svg_element_;
+  }
+  const SVGElement& SvgElement() const {
+    DCHECK(svg_element_);
+    return *svg_element_;
+  }
+
+  const SVGPropertyBase& SvgBaseValue() const {
+    DCHECK(svg_base_value_);
+    return *svg_base_value_;
+  }
+
+ private:
+  Member<SVGElement> svg_element_ = nullptr;
+  Member<const SVGPropertyBase> svg_base_value_ = nullptr;
+};
+
+DEFINE_TYPE_CASTS(SVGInterpolationEnvironment,
+                  InterpolationEnvironment,
+                  value,
+                  value->IsSVG(),
+                  value.IsSVG());
+
+}  // namespace blink
+
+#endif  // SVGInterpolationEnvironment_h