compositor-worker: Add CompositorProxyClient worker client of CompositorWorker.

third_party/WebKit/Source/core/loader/EmptyClients.h

 /*
  * Copyright (C) 2006 Eric Seidel (eric@webkit.org)
  * Copyright (C) 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.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
@@ skipping 153 matching lines @@
     void setHasScrollEventHandlers(bool) override {}
     bool hasScrollEventHandlers() const override { return false; }
 
     void setTouchAction(TouchAction) override {}
 
     void didAssociateFormControls(const HeapVector<Member<Element>>&, LocalFrame*) override {}
 
     void annotatedRegionsChanged() override {}
     String acceptLanguages() override;
 
+    CompositorProxyClient* createCompositorProxyClient() override { return nullptr; }
+
     void registerPopupOpeningObserver(PopupOpeningObserver*) override {}
     void unregisterPopupOpeningObserver(PopupOpeningObserver*) override {}
 
     PassOwnPtr<WebFrameScheduler> createFrameScheduler(BlameContext*) override;
 };
 
 class CORE_EXPORT EmptyFrameLoaderClient : public FrameLoaderClient {
     WTF_MAKE_NONCOPYABLE(EmptyFrameLoaderClient);
 public:
     static EmptyFrameLoaderClient* create() { return new EmptyFrameLoaderClient; }
@@ skipping 144 matching lines @@
     ~EmptyContextMenuClient() override {}
     void showContextMenu(const ContextMenu*) override {}
     void clearContextMenu() override {}
 };
 
 CORE_EXPORT void fillWithEmptyClients(Page::PageClients&);
 
 } // namespace blink
 
 #endif // EmptyClients_h