media: Always define |cdm_id| in CdmContext.

content/renderer/media/crypto/proxy_media_keys.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 "content/renderer/media/crypto/proxy_media_keys.h"
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
@@ skipping 107 matching lines @@
   // TODO(xhwang): Check key system and platform support for LoadSession in
   // blink and add NOTREACHED() here. See http://crbug.com/384152
   promise->reject(NOT_SUPPORTED_ERROR, 0, "RemoveSession() not supported.");
 }
 
 media::CdmContext* ProxyMediaKeys::GetCdmContext() {
   return this;
 }
 
 media::Decryptor* ProxyMediaKeys::GetDecryptor() {
-  return NULL;
+  return nullptr;
 }
 
 int ProxyMediaKeys::GetCdmId() const {
   return cdm_id_;
 }
 
 void ProxyMediaKeys::OnSessionMessage(
     const std::string& session_id,
     media::MediaKeys::MessageType message_type,
     const std::vector<uint8>& message,
@@ skipping 59 matching lines @@
       session_expiration_update_cb_(session_expiration_update_cb) {
   cdm_id_ = manager->RegisterMediaKeys(this);
 }
 
 void ProxyMediaKeys::InitializeCdm(const std::string& key_system,
                                    const GURL& security_origin) {
   manager_->InitializeCdm(cdm_id_, this, key_system, security_origin);
 }
 
 }  // namespace content