CompositorWorkerProxyClientImpl to CompositorProxy cross thread reference is using WeakMember

third_party/WebKit/Source/modules/compositorworker/CompositorWorkerMessagingProxy.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/CompositorWorkerMessagingProxy.h"
 
 #include "core/workers/WorkerThreadStartupData.h"
 #include "modules/compositorworker/CompositorWorkerThread.h"
 #include <memory>
 
 namespace blink {
 
 CompositorWorkerMessagingProxy::CompositorWorkerMessagingProxy(
     InProcessWorkerBase* worker,
     WorkerClients* workerClients)
-    : InProcessWorkerMessagingProxy(worker, workerClients) {}
+    : InProcessWorkerMessagingProxy(worker, workerClients) {
+  DCHECK(isMainThread());
+}
 
 CompositorWorkerMessagingProxy::~CompositorWorkerMessagingProxy() {}
 
 std::unique_ptr<WorkerThread>
 CompositorWorkerMessagingProxy::createWorkerThread(double originTime) {
   return CompositorWorkerThread::create(loaderProxy(), workerObjectProxy(),
                                         originTime);
 }
 
 }  // namespace blink