Convert enable_plugins to a buildflag header.

chrome/test/base/test_switches.cc

Index: chrome/test/base/test_switches.cc
diff --git a/chrome/test/base/test_switches.cc b/chrome/test/base/test_switches.cc
index 881621735339aad37998e77101cfb01739d8c07c..03e98b48e27506d94541f7a6815068a88be9d7a6 100644
--- a/chrome/test/base/test_switches.cc
+++ b/chrome/test/base/test_switches.cc
@@ -4,13 +4,14 @@
 
 #include "build/build_config.h"
 #include "chrome/test/base/test_switches.h"
+#include "ppapi/features/features.h"
 
 namespace switches {
 
 // Also emit full event trace logs for successful tests.
 const char kAlsoEmitSuccessLogs[] = "also-emit-success-logs";
 
-#if defined(ENABLE_PLUGINS)
+#if BUILDFLAG(ENABLE_PLUGINS)
 // Makes browser pixel tests overwrite the reference if it does not match.
 const char kRebaselinePixelTests[] = "rebaseline-pixel-tests";
 #endif