workers: Move ownership of WebThread from WorkerThread

Source/modules/compositorworker/CompositorWorkerThread.cpp

 // 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.
 
 #include "config.h"
 #include "modules/compositorworker/CompositorWorkerThread.h"
 
 #include "bindings/core/v8/V8Initializer.h"
 #include "core/workers/WorkerObjectProxy.h"
 #include "core/workers/WorkerThreadStartupData.h"
 #include "modules/compositorworker/CompositorWorkerGlobalScope.h"
 #include "public/platform/Platform.h"
 
 namespace blink {
 
 PassRefPtr<CompositorWorkerThread> CompositorWorkerThread::create(PassRefPtr<WorkerLoaderProxy> workerLoaderProxy, WorkerObjectProxy& workerObjectProxy, double timeOrigin, PassOwnPtr<WorkerThreadStartupData> startupData)
 {
     ASSERT(isMainThread());
     return adoptRef(new CompositorWorkerThread(workerLoaderProxy, workerObjectProxy, timeOrigin, startupData));
 }
 
 CompositorWorkerThread::CompositorWorkerThread(PassRefPtr<WorkerLoaderProxy> workerLoaderProxy, WorkerObjectProxy& workerObjectProxy, double timeOrigin, PassOwnPtr<WorkerThreadStartupData> startupData)
-    : WorkerThread("CompositorWorker Thread", workerLoaderProxy, workerObjectProxy, startupData)
+    : WorkerThread(workerLoaderProxy, workerObjectProxy, startupData)
     , m_workerObjectProxy(workerObjectProxy)
     , m_timeOrigin(timeOrigin)
 {
 }
 
 CompositorWorkerThread::~CompositorWorkerThread()
 {
 }
 
 PassRefPtrWillBeRawPtr<WorkerGlobalScope> CompositorWorkerThread::createWorkerGlobalScope(PassOwnPtr<WorkerThreadStartupData> startupData)
 {
     return CompositorWorkerGlobalScope::create(this, startupData, m_timeOrigin);
 }
 
+WebThreadSupportingGC& CompositorWorkerThread::backingThread()
+{
+    if (!m_thread)
+        m_thread = WebThreadSupportingGC::create("CompositorWorker Thread");
+    return *m_thread.get();
+}
+
 } // namespace blink