compositor-worker: Initialize CW machinery plumbing to compositor and fire CW rAF callbacks.

third_party/WebKit/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 "modules/compositorworker/CompositorWorkerThread.h"
 
 #include "bindings/core/v8/V8GCController.h"
 #include "bindings/core/v8/V8Initializer.h"
 #include "core/workers/WorkerBackingThread.h"
 #include "core/workers/WorkerObjectProxy.h"
@@ skipping 53 matching lines @@
 {
     return *BackingThreadHolder::instance().thread();
 }
 
 WorkerGlobalScope*CompositorWorkerThread::createWorkerGlobalScope(PassOwnPtr<WorkerThreadStartupData> startupData)
 {
     TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("compositor-worker"), "CompositorWorkerThread::createWorkerGlobalScope");
     return CompositorWorkerGlobalScope::create(this, startupData, m_timeOrigin);
 }
 
+void CompositorWorkerThread::ensureSharedBackingThread()
+{
+    BackingThreadHolder::instance();
+}
+
 void CompositorWorkerThread::clearSharedBackingThread()
 {
     BackingThreadHolder::instance().clear();
 }
 
 void CompositorWorkerThread::resetSharedBackingThreadForTest()
 {
     BackingThreadHolder::instance().resetForTest();
 }
 
 } // namespace blink