Remove unnecessary casts in AudioManagerDeleter on Mac.

media/audio/audio_manager.h

 // Copyright (c) 2012 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 MEDIA_AUDIO_AUDIO_MANAGER_H_
 #define MEDIA_AUDIO_AUDIO_MANAGER_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 243 matching lines @@
   // Limits the number of streams that can be created for testing purposes.
   virtual void SetMaxStreamCountForTesting(int max_input, int max_output);
 
  protected:
   AudioManager(scoped_refptr<base::SingleThreadTaskRunner> task_runner,
                scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner);
   virtual ~AudioManager();
 
  private:
   friend class base::DeleteHelper<AudioManager>;
+  friend class AudioManagerDeleter;
 
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner_;
   DISALLOW_COPY_AND_ASSIGN(AudioManager);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_MANAGER_H_