[worklets] Introduce ThreadedWorkletMessagingProxy and AnimationWorkletMessagaingProxy.

third_party/WebKit/Source/modules/compositorworker/AnimationWorklet.h

Index: third_party/WebKit/Source/modules/compositorworker/AnimationWorklet.h
diff --git a/third_party/WebKit/Source/modules/compositorworker/AnimationWorklet.h b/third_party/WebKit/Source/modules/compositorworker/AnimationWorklet.h
index c77fd8fe5ecdcdd55ad5dedacdb75c5382f31b4a..40f7e8a36635dcecc26c91b86e38e72698e73eec 100644
--- a/third_party/WebKit/Source/modules/compositorworker/AnimationWorklet.h
+++ b/third_party/WebKit/Source/modules/compositorworker/AnimationWorklet.h
@@ -12,7 +12,7 @@
 namespace blink {
 
 class LocalFrame;
-class ThreadedWorkletGlobalScopeProxy;
+class ThreadedWorkletMessagingProxy;
 class WorkletGlobalScopeProxy;
 
 class MODULES_EXPORT AnimationWorklet final : public Worklet {
@@ -21,6 +21,9 @@ public:
     static AnimationWorklet* create(LocalFrame*);
     ~AnimationWorklet() override;
 
+    void initialize() final;
+    bool isInitialized() const final;
+
     WorkletGlobalScopeProxy* workletGlobalScopeProxy() const final;
 
     DECLARE_VIRTUAL_TRACE();
@@ -28,8 +31,9 @@ public:
 private:
     explicit AnimationWorklet(LocalFrame*);
 
-    // TODO(ikilpatrick): this will change to a raw ptr once we have a thread.
-    std::unique_ptr<ThreadedWorkletGlobalScopeProxy> m_workletGlobalScopeProxy;
+    // The proxy outlives the worklet as it is used to perform thread shutdown,
+    // it deletes itself once this has occured.
+    ThreadedWorkletMessagingProxy* m_workletMessagingProxy;
 };
 
 } // namespace blink