Implement "Key Presence" step in "Encrypted Block Encounted" algorithm in EME.

media/crypto/aes_decryptor.cc

 // 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.
 
 #include "media/crypto/aes_decryptor.h"
 
 #include <vector>
 
 #include "base/logging.h"
 #include "base/stl_util.h"
@@ skipping 284 matching lines @@
     DVLOG(1) << "Decryption failed.";
     decrypt_cb.Run(kError, NULL);
     return;
   }
 
   decrypted->SetTimestamp(encrypted->GetTimestamp());
   decrypted->SetDuration(encrypted->GetDuration());
   decrypt_cb.Run(kSuccess, decrypted);
 }
 
+void AesDecryptor::Stop() {
+}
+
 void AesDecryptor::SetKey(const std::string& key_id,
                           scoped_ptr<DecryptionKey> decryption_key) {
   base::AutoLock auto_lock(key_map_lock_);
   KeyMap::iterator found = key_map_.find(key_id);
   if (found != key_map_.end()) {
     delete found->second;
     key_map_.erase(found);
   }
   key_map_[key_id] = decryption_key.release();
 }
@@ skipping 33 matching lines @@
     return false;
 
   hmac_key_ = DeriveKey(secret_, kWebmHmacSeed, kWebmSha1DigestSize);
   if (hmac_key_.empty())
     return false;
 
   return true;
 }
 
 }  // namespace media