Convert USE_PROPRIETARY_CODECS to a buildflag header.

components/cdm/common/widevine_drm_delegate_android.cc

Index: components/cdm/common/widevine_drm_delegate_android.cc
diff --git a/components/cdm/common/widevine_drm_delegate_android.cc b/components/cdm/common/widevine_drm_delegate_android.cc
index d8e0f4391269f302d1016057aec9e516d68562b7..8c96a12587242f1177ed28ccb205084c34fbb3e6 100644
--- a/components/cdm/common/widevine_drm_delegate_android.cc
+++ b/components/cdm/common/widevine_drm_delegate_android.cc
@@ -6,6 +6,7 @@
 
 #include "base/macros.h"
 #include "media/cdm/cenc_utils.h"
+#include "media/media_features.h"
 
 namespace cdm {
 
@@ -34,7 +35,7 @@ bool WidevineDrmDelegateAndroid::OnCreateSession(
   if (init_data_type != media::EmeInitDataType::CENC)
     return true;
 
-#if defined(USE_PROPRIETARY_CODECS)
+#if BUILDFLAG(USE_PROPRIETARY_CODECS)
   // Widevine MediaDrm plugin only accepts the "data" part of the PSSH box as
   // the init data when using MP4 container.
   return media::GetPsshData(init_data, GetUUID(), init_data_out);