Fix a crash where the ResourceMessageFilter is deleted

chrome/browser/worker_host/worker_service.h

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_WORKER_HOST__WORKER_SERVICE_H_
 #define CHROME_BROWSER_WORKER_HOST__WORKER_SERVICE_H_
 
 #include <list>
 
 #include "base/basictypes.h"
 #include "base/singleton.h"
+#include "chrome/common/notification_observer.h"
 #include "googleurl/src/gurl.h"
 
 namespace IPC {
 class Message;
 }
 
 class MessageLoop;
 class WorkerProcessHost;
 class ResourceMessageFilter;
 
-class WorkerService {
+class WorkerService : public NotificationObserver {
  public:
   // Returns the WorkerService singleton.
   static WorkerService* GetInstance();
 
   // Creates a dedicated worker.  Returns true on success.
   bool CreateDedicatedWorker(const GURL &url,
                              int render_view_route_id,
                              ResourceMessageFilter* filter,
                              int renderer_route_id);
 
   // Called by ResourceMessageFilter when a message from the renderer comes that
   // should be forwarded to the worker process.
   void ForwardMessage(const IPC::Message& message);
 
-  // Called by ResourceMessageFilter when it's destructed so that all the
-  // WorkerProcessHost objects can remove their pointers to it.
-  void RendererShutdown(ResourceMessageFilter* filter);
+  // NotificationObserver interface.
+  void Observe(NotificationType type,
+               const NotificationSource& source,
+               const NotificationDetails& details);
 
  private:
   friend struct DefaultSingletonTraits<WorkerService>;
 
   WorkerService();
   ~WorkerService();
 
   // Returns a WorkerProcessHost object if one exists for the given domain, or
   // NULL if there are no such workers yet.
   WorkerProcessHost* GetProcessForDomain(const GURL& url);
 
   // Returns a WorkerProcessHost based on a strategy of creating one worker per
   // core.
   WorkerProcessHost* GetProcessToFillUpCores();
 
   // Returns the WorkerProcessHost from the existing set that has the least
   // number of worker instance running.
   WorkerProcessHost* GetLeastLoadedWorker();
 
   int next_worker_route_id_;
 
   DISALLOW_COPY_AND_ASSIGN(WorkerService);
 };
 
 #endif  // CHROME_BROWSER_WORKER_HOST__WORKER_SERVICE_H_