Move ENABLE_PEPPER_CDMS to a buildflag header.

media/base/key_systems_unittest.cc

Index: media/base/key_systems_unittest.cc
diff --git a/media/base/key_systems_unittest.cc b/media/base/key_systems_unittest.cc
index b8dac94b9c58a90e8450c9f37a6321929a9558ee..a9ed6fa8ff298283f0538019bd26ec612039a4bd 100644
--- a/media/base/key_systems_unittest.cc
+++ b/media/base/key_systems_unittest.cc
@@ -18,6 +18,7 @@
 #include "media/base/media.h"
 #include "media/base/media_client.h"
 #include "testing/gtest/include/gtest/gtest.h"
+#include "third_party/widevine/cdm/cdm_features.h"
 
 namespace media {
 
@@ -423,7 +424,7 @@ TEST_F(KeySystemsTest, Basic_UnrecognizedKeySystem) {
   EXPECT_EQ("Unknown", GetKeySystemNameForUMA(kUnrecognized));
   EXPECT_FALSE(CanUseAesDecryptor(kUnrecognized));
 
-#if defined(ENABLE_PEPPER_CDMS)
+#if BUILDFLAG(ENABLE_PEPPER_CDMS)
   std::string type;
 #if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
   EXPECT_DEATH(type = GetPepperType(kUnrecognized),
@@ -442,7 +443,7 @@ TEST_F(KeySystemsTest, Basic_UsesAesDecryptor) {
   EXPECT_EQ("UseAes", GetKeySystemNameForUMA(kUsesAes));
 
   EXPECT_TRUE(CanUseAesDecryptor(kUsesAes));
-#if defined(ENABLE_PEPPER_CDMS)
+#if BUILDFLAG(ENABLE_PEPPER_CDMS)
   std::string type;
 #if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
   EXPECT_DEATH(type = GetPepperType(kUsesAes),
@@ -599,9 +600,9 @@ TEST_F(KeySystemsTest, Basic_ExternalDecryptor) {
       kVideoWebM, no_codecs(), kExternal));
 
   EXPECT_FALSE(CanUseAesDecryptor(kExternal));
-#if defined(ENABLE_PEPPER_CDMS)
+#if BUILDFLAG(ENABLE_PEPPER_CDMS)
   EXPECT_EQ("application/x-ppapi-external-cdm", GetPepperType(kExternal));
-#endif  // defined(ENABLE_PEPPER_CDMS)
+#endif  // BUILDFLAG(ENABLE_PEPPER_CDMS)
 }
 
 TEST_F(