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 249 matching lines @@
                                     const std::string& session_id) {
 }
 
 void AesDecryptor::Decrypt(const scoped_refptr<DecoderBuffer>& encrypted,
                            const DecryptCB& decrypt_cb) {
   CHECK(encrypted->GetDecryptConfig());
   const std::string& key_id = encrypted->GetDecryptConfig()->key_id();
 
   DecryptionKey* key = GetKey(key_id);
   if (!key) {
-    // TODO(xhwang): Fire a need_key event here and add a test.
     DVLOG(1) << "Could not find a matching key for the given key ID.";
-    decrypt_cb.Run(kError, NULL);
+    decrypt_cb.Run(kNoKey, NULL);
     return;
   }
 
   int checksum_size = encrypted->GetDecryptConfig()->checksum().size();
   // According to the WebM encrypted specification, it is an open question
   // what should happen when a frame fails the integrity check.
   // http://wiki.webmproject.org/encryption/webm-encryption-rfc
   if (checksum_size > 0 &&
       !key->hmac_key().empty() &&
       !CheckData(*encrypted, key->hmac_key())) {
@@ skipping 20 matching lines @@
       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