[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:
+  static AnimatorDefinition* Create(v8::Isolate*,
+                                    v8::Local<v8::Function> constructor,
+                                    v8::Local<v8::Function> animate);
+
+  ~AnimatorDefinition();
+  DEFINE_INLINE_TRACE() {}
+
+  v8::Local<v8::Function> ConstructorLocal(v8::Isolate*);
+
+ private:
+  AnimatorDefinition(v8::Isolate*,
+                     v8::Local<v8::Function> constructor,
+                     v8::Local<v8::Function> animate);
+
+  // 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> m_constructor;
+  ScopedPersistent<v8::Function> m_animate;

[haraken, 2017/05/20 00:35:29]

m_animate is not used...?

[haraken, 2017/05/20 00:35:29]

Ditto. We should consider using the wrapper tracing.

[majidvp, 2017/05/24 14:24:16]

The patch is adding the validation code for |m_animate| as part of the 
registration process for an animator. The function is used in
a follow up patch. Here is WIP for that:
https://codereview.chromium.org/2894233002/

+};
+
+}  // namespace blink
+
+#endif  // AnimatorDefinition_h