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

third_party/WebKit/Source/core/page/ChromeClient.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple, Inc. All rights
  * reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  * Copyright (C) 2012 Samsung Electronics. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 32 matching lines @@
 #include "wtf/Optional.h"
 #include "wtf/Vector.h"
 #include <memory>
 
 namespace blink {
 
 class AXObject;
 class ColorChooser;
 class ColorChooserClient;
 class CompositorAnimationTimeline;
-class CompositorProxyClient;
+class CompositorProxyClientFactory;
 class DateTimeChooser;
 class DateTimeChooserClient;
 class Element;
 class FileChooser;
 class FloatPoint;
 class Frame;
 class GraphicsLayer;
 class HTMLFormControlElement;
 class HTMLInputElement;
 class HTMLSelectElement;
@@ skipping 246 matching lines @@
 
   virtual void showUnhandledTapUIIfNeeded(IntPoint, Node*, bool) {}
 
   virtual void onMouseDown(Node*) {}
 
   virtual void didUpdateBrowserControls() const {}
 
   virtual void registerPopupOpeningObserver(PopupOpeningObserver*) = 0;
   virtual void unregisterPopupOpeningObserver(PopupOpeningObserver*) = 0;
 
-  virtual CompositorProxyClient* createCompositorProxyClient(LocalFrame*) = 0;
+  virtual CompositorProxyClientFactory* compositorProxyClientFactory(
+      LocalFrame*) = 0;
 
   virtual FloatSize elasticOverscroll() const { return FloatSize(); }
 
   // Called when observed XHR, fetch, and other fetch request with non-GET
   // method is initiated from javascript. At this time, it is not guaranteed
   // that this is comprehensive.
   virtual void didObserveNonGetFetchFromScript() const {}
 
   virtual std::unique_ptr<WebFrameScheduler> createFrameScheduler(
       BlameContext*) = 0;
@@ skipping 27 matching lines @@
 
   LayoutPoint m_lastToolTipPoint;
   String m_lastToolTipText;
 
   FRIEND_TEST_ALL_PREFIXES(ChromeClientTest, SetToolTipFlood);
 };
 
 }  // namespace blink
 
 #endif  // ChromeClient_h