workers: Rename WorkerThread to WorkerScript.

Source/modules/compositorworker/CompositorWorkerMessagingProxy.h

 // Copyright 2015 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 CompositorWorkerMessagingProxy_h
 #define CompositorWorkerMessagingProxy_h
 
 #include "core/workers/WorkerMessagingProxy.h"
 
 namespace blink {
 
 class CompositorWorkerMessagingProxy final : public WorkerMessagingProxy {
 public:
     CompositorWorkerMessagingProxy(InProcessWorkerBase*, PassOwnPtrWillBeRawPtr<WorkerClients>);
 
 protected:
     virtual ~CompositorWorkerMessagingProxy();
 
-    virtual PassRefPtr<WorkerThread> createWorkerThread(double originTime, PassOwnPtr<WorkerThreadStartupData>);
+    virtual PassRefPtr<WorkerScript> createWorkerScript(double originTime, PassOwnPtr<WorkerScriptStartupData>);
 };
 
 } // namespace blink
 
 #endif // CompositorWorkerMessagingProxy_h