Introduce AnimationWorkletProxyClient and necessary plumbing to get it in worklet messaging proxy.

third_party/WebKit/Source/modules/compositorworker/CompositorWorker.cpp

Index: third_party/WebKit/Source/modules/compositorworker/CompositorWorker.cpp
diff --git a/third_party/WebKit/Source/modules/compositorworker/CompositorWorker.cpp b/third_party/WebKit/Source/modules/compositorworker/CompositorWorker.cpp
index 26bfa946dcd315b156ddf338a3cb0321c295029a..82eabcff1f24671ce4f115afac7a9641027652fc 100644
--- a/third_party/WebKit/Source/modules/compositorworker/CompositorWorker.cpp
+++ b/third_party/WebKit/Source/modules/compositorworker/CompositorWorker.cpp
@@ -5,7 +5,7 @@
 #include "modules/compositorworker/CompositorWorker.h"
 
 #include "bindings/core/v8/ExceptionState.h"
-#include "core/dom/CompositorProxyClient.h"
+#include "core/dom/CompositorWorkerProxyClient.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/frame/LocalFrame.h"
@@ -55,10 +55,10 @@ CompositorWorker::createInProcessWorkerMessagingProxy(
     ExecutionContext* context) {
   Document* document = toDocument(context);
   WorkerClients* workerClients = WorkerClients::create();
-  provideCompositorProxyClientTo(
-      workerClients,
-      document->frame()->chromeClient().createCompositorProxyClient(
-          document->frame()));
+  CompositorWorkerProxyClient* client =
+      document->frame()->chromeClient().createCompositorWorkerProxyClient(
+          document->frame());
+  provideCompositorWorkerProxyClientTo(workerClients, client);
   return new CompositorWorkerMessagingProxy(this, workerClients);
 }