Extract CdmManager from MojoCdmService.

media/cdm/cdm_manager.cc

+// Copyright 2017 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/cdm/cdm_manager.h"
+
+#include <utility>
+
+#include "base/logging.h"
+#include "media/base/content_decryption_module.h"
+
+namespace media {
+
+CdmManager::CdmManager() {}
+
+CdmManager::~CdmManager() {}
+
+// static
+CdmManager* CdmManager::GetInstance() {
+  static CdmManager* manager = new CdmManager();
+  return manager;
+}
+
+scoped_refptr<ContentDecryptionModule> CdmManager::GetCdm(int cdm_id) {
+  base::AutoLock lock(lock_);
+  auto iter = cdm_map_.find(cdm_id);
+  return iter == cdm_map_.end() ? nullptr : iter->second;
+}
+
+void CdmManager::RegisterCdm(int cdm_id,
+                             scoped_refptr<ContentDecryptionModule> cdm) {
+  base::AutoLock lock(lock_);
+  DCHECK(!cdm_map_.count(cdm_id));
+  cdm_map_[cdm_id] = cdm;
+}
+
+void CdmManager::UnregisterCdm(int cdm_id) {
+  base::AutoLock lock(lock_);
+  DCHECK(cdm_map_.count(cdm_id));
+  cdm_map_.erase(cdm_id);
+}
+
+}  // namespace media