RefCounted types should not have public destructors, delegate cleanup

content/public/browser/worker_service_observer.h

Index: content/public/browser/worker_service_observer.h
diff --git a/content/public/browser/worker_service_observer.h b/content/public/browser/worker_service_observer.h
index e09051122f293509f866d1720b541020210c6cf6..e9d6abbc2929cb6037502edfd7d2aa38dfab63c7 100644
--- a/content/public/browser/worker_service_observer.h
+++ b/content/public/browser/worker_service_observer.h
@@ -15,13 +15,14 @@ namespace content {
 
 class WorkerServiceObserver {
  public:
-  virtual ~WorkerServiceObserver() {}
-
   virtual void WorkerCreated(const GURL& url,
                              const string16& name,
                              int process_id,
                              int route_id) {}
   virtual void WorkerDestroyed(int process_id, int route_id) {}
+
+ protected:
+  virtual ~WorkerServiceObserver() {}
 };
 
 }  // namespace content