compositor-worker: Introduce CompositorWorker.

Source/core/dom/ExecutionContext.h

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * Copyright (C) 2012 Google Inc. 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
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 49 matching lines @@
     : public ContextLifecycleNotifier, public WillBeHeapSupplementable<ExecutionContext> {
     WTF_MAKE_NONCOPYABLE(ExecutionContext);
 public:
     DECLARE_VIRTUAL_TRACE();
 
     virtual bool isDocument() const { return false; }
     virtual bool isWorkerGlobalScope() const { return false; }
     virtual bool isDedicatedWorkerGlobalScope() const { return false; }
     virtual bool isSharedWorkerGlobalScope() const { return false; }
     virtual bool isServiceWorkerGlobalScope() const { return false; }
+    virtual bool isCompositorWorkerGlobalScope() const { return false; }
     virtual bool isJSExecutionForbidden() const { return false; }
 
     virtual bool isContextThread() const { return true; }
 
     SecurityOrigin* securityOrigin();
     ContentSecurityPolicy* contentSecurityPolicy();
     const KURL& url() const;
     KURL completeURL(const String& url) const;
     virtual void disableEval(const String& errorMessage) = 0;
     virtual LocalDOMWindow* executingWindow() { return 0; }
@@ skipping 95 matching lines @@
     // |allowWindowInteraction()| and |consumeWindowInteraction()| in order to
     // increment and decrement the counter.
     int m_windowInteractionTokens;
 
     Deque<OwnPtr<SuspendableTask>> m_suspendedTasks;
 };
 
 } // namespace blink
 
 #endif // ExecutionContext_h