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..579ead70be45cb443b39839132e20402738f95e6 100644
--- a/Source/core/workers/WorkerObjectProxy.h
+++ b/Source/core/workers/WorkerObjectProxy.h
@@ -50,7 +50,7 @@ class WorkerMessagingProxy;
 // WorkerMessagingProxy on the worker object thread.
 //
 // Used only by Dedicated Worker.

[kinuko, 2015/06/08 04:36:58]

Looks like this comment is stale, could we update?  (Now could be used by
in-process workers like DedicatedWorker and CompositorWorker)

[sof, 2015/06/08 08:18:16]

Certainly, done.

-class CORE_EXPORT WorkerObjectProxy final : public WorkerReportingProxy {
+class CORE_EXPORT WorkerObjectProxy : public WorkerReportingProxy {
 public:
     static PassOwnPtr<WorkerObjectProxy> create(ExecutionContext*, WorkerMessagingProxy*);

[kinuko, 2015/06/08 04:36:59]

Could we have ASSERT(!messagingProxy) in .cc so that instantiating this using
public method wouldn't end up with null messaging proxy?

[sof, 2015/06/08 08:18:16]

That's well worth it, now done.

     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;