Add Decryptor interface.

media/crypto/decryptor.cc

Index: media/crypto/decryptor.cc
diff --git a/media/crypto/decryptor.cc b/media/crypto/decryptor.cc
new file mode 100644
index 0000000000000000000000000000000000000000..d0b6b1ac0ea4f10ff6a30974f7331fb66158d912
--- /dev/null
+++ b/media/crypto/decryptor.cc
@@ -0,0 +1,18 @@
+// 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/decryptor.h"
+#include "media/crypto/decryptor_client.h"
+
+namespace media {
+
+Decryptor::Decryptor(DecryptorClient* client) : client_(client) {}
+
+Decryptor::~Decryptor() {}
+
+DecryptorClient* Decryptor::client() const {
+  return client_;
+}
+
+}  // namespace media