Rename 'UseCounter::observe' to 'UseCounter::count'.

Source/core/workers/Worker.cpp

Index: Source/core/workers/Worker.cpp
diff --git a/Source/core/workers/Worker.cpp b/Source/core/workers/Worker.cpp
index 3f4632745c330241e422536cd44ea90bc9fe4045..f6389c19426cd65e8dac2088eecf88a14094f22b 100644
--- a/Source/core/workers/Worker.cpp
+++ b/Source/core/workers/Worker.cpp
@@ -58,7 +58,7 @@ inline Worker::Worker(ScriptExecutionContext* context)
 PassRefPtr<Worker> Worker::create(ScriptExecutionContext* context, const String& url, ExceptionCode& ec)
 {
     ASSERT(isMainThread());
-    UseCounter::observe(static_cast<Document*>(context)->domWindow(), UseCounter::WorkerStart);
+    UseCounter::count(static_cast<Document*>(context)->domWindow(), UseCounter::WorkerStart);
 
     RefPtr<Worker> worker = adoptRef(new Worker(context));