[animation-worklet] Implement registerAnimator in worklet scope

third_party/WebKit/Source/modules/compositorworker/Animator.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 Animator_h
+#define Animator_h
+
+#include "platform/bindings/ScopedPersistent.h"
+#include "platform/heap/Handle.h"
+#include "v8/include/v8.h"
+
+namespace blink {
+
+class AnimatorDefinition;
+
+class Animator final : public GarbageCollectedFinalized<Animator> {
+ public:
+  Animator(v8::Isolate*, AnimatorDefinition*, v8::Local<v8::Object> instance);
+  ~Animator();
+  DECLARE_TRACE();
+
+ private:
+  // This object keeps the definition object, and animator instance alive.
+  // It needs to be destroyed to break a reference cycle between it and the
+  // AnimationWorkletGlobalScope. The reference cycle is broken at
+  // |AnimationWorkletGlobalScope::Dispose()|.
+  Member<AnimatorDefinition> definition_;
+  ScopedPersistent<v8::Object> instance_;
+};
+
+}  // namespace blink
+
+#endif  // Animator_h