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

third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp

Index: third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp
diff --git a/third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp b/third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp
index e5a1a5fe098acadcbd490dc622671244d3e380cd..68807bd68ab5dc2fcd0d8b55e1511db1692eabe1 100644
--- a/third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp
+++ b/third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp
@@ -59,7 +59,7 @@
 #include "public/web/WebWidgetClient.h"
 #include "web/CompositionUnderlineVectorBuilder.h"
 #include "web/CompositorMutatorImpl.h"
-#include "web/CompositorProxyClientImpl.h"
+#include "web/CompositorWorkerProxyClientImpl.h"
 #include "web/ContextMenuAllowedScope.h"
 #include "web/InspectorOverlay.h"
 #include "web/PageOverlay.h"
@@ -133,6 +133,7 @@ WebFrameWidgetImpl::~WebFrameWidgetImpl() {}
 DEFINE_TRACE(WebFrameWidgetImpl) {
   visitor->trace(m_localRoot);
   visitor->trace(m_mouseCaptureNode);
+  visitor->trace(m_proxyClientFactory);
 }
 
 // WebWidget ------------------------------------------------------------------
@@ -430,14 +431,18 @@ void WebFrameWidgetImpl::scheduleAnimation() {
     m_client->scheduleAnimation();
 }
 
-CompositorProxyClient* WebFrameWidgetImpl::createCompositorProxyClient() {
-  if (!m_mutator) {
+CompositorProxyClientFactory*
+WebFrameWidgetImpl::compositorProxyClientFactory() {
+  if (!m_proxyClientFactory) {
     std::unique_ptr<CompositorMutatorClient> mutatorClient =
         CompositorMutatorImpl::createClient();
     m_mutator = static_cast<CompositorMutatorImpl*>(mutatorClient->mutator());
     m_layerTreeView->setMutatorClient(std::move(mutatorClient));
+
+    m_proxyClientFactory = new CompositorProxyClientFactoryImpl(m_mutator);
   }
-  return new CompositorProxyClientImpl(m_mutator);
+
+  return m_proxyClientFactory;
 }
 
 void WebFrameWidgetImpl::applyViewportDeltas(