compositor-worker: Keep worker backing thread alive for the lifetime of the compositor thread.

third_party/WebKit/Source/modules/compositorworker/CompositorWorker.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/CompositorWorker.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/workers/WorkerClients.h"
 #include "modules/EventTargetModules.h"
 #include "modules/compositorworker/CompositorWorkerMessagingProxy.h"
+#include "modules/compositorworker/CompositorWorkerThread.h"
 
 namespace blink {
 
 inline CompositorWorker::CompositorWorker(ExecutionContext* context)
     : InProcessWorkerBase(context)
 {
 }
 
 CompositorWorker* CompositorWorker::create(ExecutionContext* context, const String& url, ExceptionState& exceptionState)
 {
     ASSERT(isMainThread());
     Document* document = toDocument(context);
     if (!document->page()) {
         exceptionState.throwDOMException(InvalidAccessError, "The context provided is invalid.");
         return nullptr;
     }
     CompositorWorker* worker = new CompositorWorker(context);
+
+    // Ensure the compositor worker backing thread is ready before we try to
+    // initialize the CompositorWorker so that we can construct oilpan
+    // objects on the compositor thread referenced from the worker clients.
+    CompositorWorkerThread::ensureSharedBackingThread();
+
     if (worker->initialize(context, url, exceptionState))
         return worker;
     return nullptr;
 }
 
 CompositorWorker::~CompositorWorker()
 {
     ASSERT(isMainThread());
 }
 
 const AtomicString& CompositorWorker::interfaceName() const
 {
     return EventTargetNames::CompositorWorker;
 }
 
 InProcessWorkerGlobalScopeProxy* CompositorWorker::createInProcessWorkerGlobalScopeProxy(ExecutionContext* worker)
 {
     ASSERT(getExecutionContext()->isDocument());
     return new CompositorWorkerMessagingProxy(this);
 }
 
 } // namespace blink