Rename FeatureObserver to UseCounter to make clear that all it stores are usage counts.

Source/WebCore/workers/Worker.cpp

 /*
  * Copyright (C) 2008, 2010 Apple Inc. All Rights Reserved.
  * Copyright (C) 2009 Google Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 18 matching lines @@
 
 #include "Worker.h"
 
 #include "DOMWindow.h"
 #include "CachedResourceLoader.h"
 #include "Document.h"
 #include "EventException.h"
 #include "EventListener.h"
 #include "EventNames.h"
 #include "ExceptionCode.h"
-#include "FeatureObserver.h"
+#include "UseCounter.h"
 #include "Frame.h"
 #include "FrameLoader.h"
 #include "InspectorInstrumentation.h"
 #include "MessageEvent.h"
 #include "TextEncoding.h"
 #include "WorkerContextProxy.h"
 #include "WorkerScriptLoader.h"
 #include "WorkerThread.h"
 #include <wtf/MainThread.h>
 
 namespace WebCore {
 
 inline Worker::Worker(ScriptExecutionContext* context)
     : AbstractWorker(context)
     , m_contextProxy(WorkerContextProxy::create(this))
 {
 }
 
 PassRefPtr<Worker> Worker::create(ScriptExecutionContext* context, const String& url, ExceptionCode& ec)
 {
     ASSERT(isMainThread());
-    FeatureObserver::observe(static_cast<Document*>(context)->domWindow(), FeatureObserver::WorkerStart);
+    UseCounter::observe(static_cast<Document*>(context)->domWindow(), UseCounter::WorkerStart);
 
     RefPtr<Worker> worker = adoptRef(new Worker(context));
 
     worker->suspendIfNeeded();
 
     KURL scriptURL = worker->resolveURL(url, ec);
     if (scriptURL.isEmpty())
         return 0;
 
     // The worker context does not exist while loading, so we must ensure that the worker object is not collected, nor are its event listeners.
@@ skipping 70 matching lines @@
             startMode = PauseWorkerContextOnStart;
         m_contextProxy->startWorkerContext(m_scriptLoader->url(), scriptExecutionContext()->userAgent(m_scriptLoader->url()), m_scriptLoader->script(), startMode);
         InspectorInstrumentation::scriptImported(scriptExecutionContext(), m_scriptLoader->identifier(), m_scriptLoader->script());
     }
     m_scriptLoader = nullptr;
 
     unsetPendingActivity(this);
 }
 
 } // namespace WebCore