Make AppShimHostManager a RefCountedThreadSafe.

apps/app_shim/app_shim_host_manager_mac.h

 // Copyright 2013 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_WEB_APPLICATIONS_APP_SHIM_HOST_MANAGER_MAC_H_
 #define CHROME_BROWSER_WEB_APPLICATIONS_APP_SHIM_HOST_MANAGER_MAC_H_
 
 #include "apps/app_shim/extension_app_shim_handler_mac.h"
-#include "base/memory/weak_ptr.h"
+#include "base/memory/ref_counted.h"
 #include "ipc/ipc_channel_factory.h"
 
 // The AppShimHostManager receives connections from app shims on a UNIX
 // socket (|factory_|) and creates a helper object to manage the connection.
 class AppShimHostManager
     : public IPC::ChannelFactory::Delegate,
-      public base::SupportsWeakPtr<AppShimHostManager> {
+      public base::RefCountedThreadSafe<AppShimHostManager> {
  public:
   AppShimHostManager();
-  virtual ~AppShimHostManager();
 
   apps::ExtensionAppShimHandler* extension_app_shim_handler() {
     return &extension_app_shim_handler_;
   }
 
  private:
+  friend class base::RefCountedThreadSafe<AppShimHostManager>;
+  virtual ~AppShimHostManager();
+
   // IPC::ChannelFactory::Delegate implementation.
   virtual void OnClientConnected(const IPC::ChannelHandle& handle) OVERRIDE;
   virtual void OnListenError() OVERRIDE;
 
   // The |factory_| must be created on a thread which allows blocking I/O, so
   // part of the initialization of this class must be carried out on the file
   // thread.
   void InitOnFileThread();
 
   // Called on the IO thread to begin listening for connections from app shims.
   void ListenOnIOThread();
 
   scoped_ptr<IPC::ChannelFactory> factory_;
 
   apps::ExtensionAppShimHandler extension_app_shim_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(AppShimHostManager);
 };
 
 #endif  // CHROME_BROWSER_WEB_APPLICATIONS_APP_SHIM_HOST_MANAGER_MAC_H_