Convert enable_plugins to a buildflag header.

chrome/browser/policy/configuration_policy_handler_list_factory.cc

Index: chrome/browser/policy/configuration_policy_handler_list_factory.cc
diff --git a/chrome/browser/policy/configuration_policy_handler_list_factory.cc b/chrome/browser/policy/configuration_policy_handler_list_factory.cc
index 48f48bd9aab72803e453eee645faad8f9299db1f..894c04a548d845cb91eff2265a28fc5c701bbb6c 100644
--- a/chrome/browser/policy/configuration_policy_handler_list_factory.cc
+++ b/chrome/browser/policy/configuration_policy_handler_list_factory.cc
@@ -51,6 +51,7 @@
 #include "components/translate/core/common/translate_pref_names.h"
 #include "components/variations/pref_names.h"
 #include "extensions/features/features.h"
+#include "ppapi/features/features.h"
 
 #if BUILDFLAG(ANDROID_JAVA_UI)
 #include "chrome/browser/search/contextual_search_policy_handler_android.h"
@@ -80,7 +81,7 @@
 #include "extensions/common/manifest.h"
 #endif
 
-#if defined(ENABLE_PLUGINS)
+#if BUILDFLAG(ENABLE_PLUGINS)
 #include "chrome/browser/plugins/plugin_policy_handler.h"
 #endif
 
@@ -926,9 +927,9 @@ std::unique_ptr<ConfigurationPolicyHandlerList> BuildHandlerList(
   handlers->AddHandler(base::WrapUnique(new DefaultGeolocationPolicyHandler()));
 #endif  // defined(OS_CHROMEOS)
 
-#if defined(ENABLE_PLUGINS)
+#if BUILDFLAG(ENABLE_PLUGINS)
   handlers->AddHandler(base::MakeUnique<PluginPolicyHandler>());
-#endif  // defined(ENABLE_PLUGINS)
+#endif  // BUILDFLAG(ENABLE_PLUGINS)
 
   return handlers;
 }