Make InterpolationEnvironment virutal

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

Index: third_party/WebKit/Source/core/animation/CSSInterpolationEnvironment.h
diff --git a/third_party/WebKit/Source/core/animation/CSSInterpolationEnvironment.h b/third_party/WebKit/Source/core/animation/CSSInterpolationEnvironment.h
new file mode 100644
index 0000000000000000000000000000000000000000..27e3caf49b1f64a0a488ea37806980a9f17edcbb
--- /dev/null
+++ b/third_party/WebKit/Source/core/animation/CSSInterpolationEnvironment.h
@@ -0,0 +1,54 @@
+// 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 CSSInterpolationEnvironment_h
+#define CSSInterpolationEnvironment_h
+
+#include "core/animation/InterpolationEnvironment.h"
+#include "core/css/resolver/StyleResolverState.h"
+
+namespace blink {
+
+class ComputedStyle;
+
+class CSSInterpolationEnvironment : public InterpolationEnvironment {
+ public:
+  explicit CSSInterpolationEnvironment(const InterpolationTypesMap& map,
+                                       StyleResolverState& state)
+      : InterpolationEnvironment(map), state_(&state), style_(state.Style()) {}
+
+  explicit CSSInterpolationEnvironment(const InterpolationTypesMap& map,
+                                       const ComputedStyle& style)
+      : InterpolationEnvironment(map), style_(&style) {}
+
+  bool IsCSS() const final { return true; }
+
+  StyleResolverState& GetState() {
+    DCHECK(state_);
+    return *state_;
+  }
+  const StyleResolverState& GetState() const {
+    DCHECK(state_);
+    return *state_;
+  }
+
+  const ComputedStyle& Style() const {
+    DCHECK(style_);
+    return *style_;
+  }
+
+ private:
+  StyleResolverState* state_ = nullptr;
+  const ComputedStyle* style_ = nullptr;
+};
+
+DEFINE_TYPE_CASTS(CSSInterpolationEnvironment,
+                  InterpolationEnvironment,
+                  value,
+                  value->IsCSS(),
+                  value.IsCSS());
+
+}  // namespace blink
+
+#endif  // CSSInterpolationEnvironment_h