Tidy up CompositorWorkerManager unit tests.

Source/core/workers/WorkerObjectProxy.h

Index: Source/core/workers/WorkerObjectProxy.h
diff --git a/Source/core/workers/WorkerObjectProxy.h b/Source/core/workers/WorkerObjectProxy.h
index 7703b8013291572c0514b89a66e90ca181b2afd0..b867e5e02affe762fe9e37cb274af370ba496862 100644
--- a/Source/core/workers/WorkerObjectProxy.h
+++ b/Source/core/workers/WorkerObjectProxy.h
@@ -49,8 +49,8 @@ class WorkerMessagingProxy;
 // the worker thread, and used just to proxy messages to the
 // WorkerMessagingProxy on the worker object thread.
 //
-// Used only by Dedicated Worker.
-class CORE_EXPORT WorkerObjectProxy final : public WorkerReportingProxy {
+// Used only by in-process workers (DedicatedWorker and CompositorWorker.)
+class CORE_EXPORT WorkerObjectProxy : public WorkerReportingProxy {
 public:
     static PassOwnPtr<WorkerObjectProxy> create(ExecutionContext*, WorkerMessagingProxy*);
     virtual ~WorkerObjectProxy() { }
@@ -71,9 +71,10 @@ public:
     virtual void workerThreadTerminated() override;
     virtual void willDestroyWorkerGlobalScope() override { }
 
-private:
+protected:
     WorkerObjectProxy(ExecutionContext*, WorkerMessagingProxy*);
 
+private:
     // These objects always outlive this proxy.
     ExecutionContext* m_executionContext;
     WorkerMessagingProxy* m_messagingProxy;