Move ENABLE_PEPPER_CDMS to a buildflag header.

components/cdm/renderer/external_clear_key_key_system_properties.cc

Index: components/cdm/renderer/external_clear_key_key_system_properties.cc
diff --git a/components/cdm/renderer/external_clear_key_key_system_properties.cc b/components/cdm/renderer/external_clear_key_key_system_properties.cc
index 5771ec2af558afca3907879462cfd46cc6db421b..a418615f3bdb249b863c150b19e3fab2371fd42f 100644
--- a/components/cdm/renderer/external_clear_key_key_system_properties.cc
+++ b/components/cdm/renderer/external_clear_key_key_system_properties.cc
@@ -6,10 +6,11 @@
 
 #include "base/logging.h"
 #include "media/base/eme_constants.h"
+#include "third_party/widevine/cdm/cdm_features.h"
 
 namespace cdm {
 
-#if defined(ENABLE_PEPPER_CDMS)
+#if BUILDFLAG(ENABLE_PEPPER_CDMS)
 const char kExternalClearKeyPepperType[] = "application/x-ppapi-clearkey-cdm";
 #endif
 
@@ -80,7 +81,7 @@ ExternalClearKeyProperties::GetDistinctiveIdentifierSupport() const {
   return media::EmeFeatureSupport::NOT_SUPPORTED;
 }
 
-#if defined(ENABLE_PEPPER_CDMS)
+#if BUILDFLAG(ENABLE_PEPPER_CDMS)
 std::string ExternalClearKeyProperties::GetPepperType() const {
   return kExternalClearKeyPepperType;
 }