Load CMA backend from shared library

chromecast/media/base/decrypt_context_clearkey.cc

-// 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.
-
-#include "chromecast/media/base/decrypt_context_clearkey.h"
-
-#include "base/logging.h"
-#include "crypto/symmetric_key.h"
-
-namespace chromecast {
-namespace media {
-
-DecryptContextClearKey::DecryptContextClearKey(crypto::SymmetricKey* key)
-    : DecryptContext(KEY_SYSTEM_CLEAR_KEY),
-      key_(key) {
-  CHECK(key);
-}
-
-DecryptContextClearKey::~DecryptContextClearKey() {
-}
-
-crypto::SymmetricKey* DecryptContextClearKey::GetKey() const {
-  return key_;
-}
-
-}  // namespace media
-}  // namespace chromecast