Refactor CdmPromise and related classes

media/base/media_keys.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 MEDIA_BASE_MEDIA_KEYS_H_
 #define MEDIA_BASE_MEDIA_KEYS_H_
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "media/base/media_export.h"
 #include "url/gurl.h"
 
 namespace base {
 class Time;
 }
 
 namespace media {
 
 class Decryptor;
 
-template <typename T>
+template <typename... T>
 class CdmPromiseTemplate;
 
 typedef CdmPromiseTemplate<std::string> NewSessionCdmPromise;
-typedef CdmPromiseTemplate<void> SimpleCdmPromise;
+typedef CdmPromiseTemplate<> SimpleCdmPromise;
 typedef std::vector<std::vector<uint8> > KeyIdsVector;
 typedef CdmPromiseTemplate<KeyIdsVector> KeyIdsPromise;
 
 // Performs media key operations.
 //
 // All key operations are called on the renderer thread. Therefore, these calls
 // should be fast and nonblocking; key events should be fired asynchronously.
 class MEDIA_EXPORT MediaKeys {
  public:
   // Reported to UMA, so never reuse a value!
@@ skipping 106 matching lines @@
                             bool has_additional_usable_key)>
     SessionKeysChangeCB;
 
 typedef base::Callback<void(const std::string& web_session_id,
                             const base::Time& new_expiry_time)>
     SessionExpirationUpdateCB;
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_MEDIA_KEYS_H_