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 4f686427e736d2b74b9d810e5e813d769d90a867..b64e2d5fbe631ce690750ce80ede82282f9fe71b 100644
--- a/third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp
+++ b/third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp
@@ -58,9 +58,10 @@
 #include "public/web/WebPlugin.h"
 #include "public/web/WebRange.h"
 #include "public/web/WebWidgetClient.h"
+#include "web/AnimationWorkletProxyClientImpl.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"
@@ -416,14 +417,24 @@ void WebFrameWidgetImpl::scheduleAnimation() {
     m_client->scheduleAnimation();
 }
 
-CompositorProxyClient* WebFrameWidgetImpl::createCompositorProxyClient() {
+CompositorProxyClient* WebFrameWidgetImpl::createCompositorProxyClient(
+    CompositorProxyClient::Type type) {
   if (!m_mutator) {
     std::unique_ptr<CompositorMutatorClient> mutatorClient =
         CompositorMutatorImpl::createClient();
     m_mutator = static_cast<CompositorMutatorImpl*>(mutatorClient->mutator());
     m_layerTreeView->setMutatorClient(std::move(mutatorClient));
   }
-  return new CompositorProxyClientImpl(m_mutator);
+
+  switch (type) {
+    case CompositorProxyClient::kWorkerClient:

[dcheng, 2017/01/24 22:56:26]

Internally, we can just share |m_mutator| initialization and construct the
appropriate object depending on which overload is called.

+      return new CompositorWorkerProxyClientImpl(m_mutator);
+    case CompositorProxyClient::kWorkletClient:
+      return new AnimationWorkletProxyClientImpl(m_mutator);
+  }
+
+  NOTREACHED() << "Unexpected CompositorProxyClient::Type: " << type;
+  return nullptr;
 }
 
 void WebFrameWidgetImpl::applyViewportDeltas(