Chromecast: guard PlayReady with C-define to prevent accidental use.

chromecast/media/base/key_systems_common.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/key_systems_common.h"
 
 #include <cstddef>
 
 #include "media/cdm/key_system_names.h"
 
 #include "widevine_cdm_version.h" // In SHARED_INTERMEDIATE_DIR.
 
 namespace chromecast {
 namespace media {
 
+#if defined(PLAYREADY_CDM_AVAILABLE)
 const char kChromecastPlayreadyKeySystem[] = "com.chromecast.playready";
+#endif  // defined(PLAYREADY_CDM_AVAILABLE)
 
 CastKeySystem GetKeySystemByName(const std::string& key_system_name) {
 #if defined(WIDEVINE_CDM_AVAILABLE)
   if (key_system_name.compare(kWidevineKeySystem) == 0) {
     return KEY_SYSTEM_WIDEVINE;
   }
 #endif  // defined(WIDEVINE_CDM_AVAILABLE)
 
 #if defined(PLAYREADY_CDM_AVAILABLE)
   if (key_system_name.compare(kChromecastPlayreadyKeySystem) == 0) {
     return KEY_SYSTEM_PLAYREADY;
   }
 #endif  // defined(PLAYREADY_CDM_AVAILABLE)
 
   if (key_system_name.compare(::media::kClearKey) == 0) {
     return KEY_SYSTEM_CLEAR_KEY;
   }
 
   return GetPlatformKeySystemByName(key_system_name);
 }
 
 }  // namespace media
 }  // namespace chromecast