[animation-worklet] Implement registerAnimator in worklet scope

third_party/WebKit/Source/modules/compositorworker/AnimatorDefinition.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 AnimatorDefinition_h
+#define AnimatorDefinition_h
+
+#include "platform/bindings/ScopedPersistent.h"
+#include "platform/heap/Handle.h"
+#include "v8/include/v8.h"
+
+namespace blink {
+
+// This class represents a valid registered Javascript animator. Note that it
+// assumed the argument passed to its constructor have been validated to have
+// proper type.
+// It can be used to instantiate new animators and also to call the Javascript
+// 'animate' callback on a given instance.
+class AnimatorDefinition final
+    : public GarbageCollectedFinalized<AnimatorDefinition> {
+ public:
+  AnimatorDefinition(v8::Isolate*,
+                     v8::Local<v8::Function> constructor,
+                     v8::Local<v8::Function> animate);
+  ~AnimatorDefinition();
+  DEFINE_INLINE_TRACE() {}
+
+  v8::Local<v8::Function> ConstructorLocal(v8::Isolate*);
+
+ private:
+  // This object keeps the constructor function, and animate function alive.
+  // It needs to be destroyed to break a reference cycle between it and the
+  // AnimationWorkletGlobalScope. This cycle is broken in
+  // |AnimationWorkletGlobalScope::Dispose()|.
+  ScopedPersistent<v8::Function> constructor_;
+  ScopedPersistent<v8::Function> animate_;
+};
+
+}  // namespace blink
+
+#endif  // AnimatorDefinition_h