media: Make MediaKeys ref-counted.

media/base/cdm_factory.h

 // Copyright 2014 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_BASE_CDM_FACTORY_H_
 #define MEDIA_BASE_CDM_FACTORY_H_
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
 #include "media/base/media_export.h"
 #include "media/base/media_keys.h"
 
 class GURL;
 
 namespace media {
 
 // Callback used when CDM is created. |error_message| only used if
 // MediaKeys is null (i.e. CDM can't be created).
-using CdmCreatedCB = base::Callback<void(scoped_ptr<MediaKeys>,
+using CdmCreatedCB = base::Callback<void(const scoped_refptr<MediaKeys>&,
                                          const std::string& error_message)>;
 
 struct CdmConfig;
 
 class MEDIA_EXPORT CdmFactory {
  public:
   CdmFactory();
   virtual ~CdmFactory();
 
   // Creates a CDM for |key_system| and returns it through |cdm_created_cb|
   // asynchronously.
   virtual void Create(
       const std::string& key_system,
       const GURL& security_origin,
       const CdmConfig& cdm_config,
       const SessionMessageCB& session_message_cb,
       const SessionClosedCB& session_closed_cb,
       const LegacySessionErrorCB& legacy_session_error_cb,
       const SessionKeysChangeCB& session_keys_change_cb,
       const SessionExpirationUpdateCB& session_expiration_update_cb,
       const CdmCreatedCB& cdm_created_cb) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CdmFactory);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_CDM_FACTORY_H_