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

third_party/WebKit/Source/web/WebFrameWidgetBase.h

 // Copyright 2016 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 WebFrameWidgetBase_h
 #define WebFrameWidgetBase_h
 
 #include "core/clipboard/DataObject.h"
 #include "public/platform/WebDragData.h"
 #include "public/web/WebFrameWidget.h"
 #include "wtf/Assertions.h"
 
 namespace blink {
 
 class CompositorAnimationTimeline;
-class CompositorProxyClient;
+class CompositorProxyClientFactory;
 class DragController;
 class GraphicsLayer;
 class WebImage;
 class WebLayer;
 class WebLocalFrameImpl;
 class WebViewImpl;
 class HitTestResult;
 struct WebPoint;
 
 class WebFrameWidgetBase : public WebFrameWidget {
  public:
   virtual bool forSubframe() const = 0;
   virtual void scheduleAnimation() = 0;
-  virtual CompositorProxyClient* createCompositorProxyClient() = 0;
+  virtual CompositorProxyClientFactory* compositorProxyClientFactory() = 0;
   virtual WebWidgetClient* client() const = 0;
 
   // Sets the root graphics layer. |GraphicsLayer| can be null when detaching
   // the root layer.
   virtual void setRootGraphicsLayer(GraphicsLayer*) = 0;
 
   // Sets the root layer. |WebLayer| can be null when detaching the root layer.
   virtual void setRootLayer(WebLayer*) = 0;
 
   // Attaches/detaches a CompositorAnimationTimeline to the layer tree.
@@ skipping 65 matching lines @@
   // When not equal to DragOperationNone, the drag data can be dropped onto the
   // current drop target in this WebView (the drop target can accept the drop).
   WebDragOperation m_dragOperation = WebDragOperationNone;
 };
 
 DEFINE_TYPE_CASTS(WebFrameWidgetBase, WebFrameWidget, widget, true, true);
 
 }  // namespace blink
 
 #endif