Convert enable_plugins to a buildflag header.

content/public/common/pepper_plugin_info.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_PUBLIC_COMMON_PEPPER_PLUGIN_INFO_H_
 #define CONTENT_PUBLIC_COMMON_PEPPER_PLUGIN_INFO_H_
 
 #include <stdint.h>
 
 #include <string>
 #include <vector>
 
 #include "base/files/file_path.h"
 #include "content/common/content_export.h"
 #include "content/public/common/webplugininfo.h"
 #include "ppapi/c/pp_module.h"
 #include "ppapi/c/ppb.h"
+#include "ppapi/features/features.h"
 
-#if !defined(ENABLE_PLUGINS)
+#if !BUILDFLAG(ENABLE_PLUGINS)
 #error "Plugins should be enabled"
 #endif
 
 namespace content {
 
 struct CONTENT_EXPORT PepperPluginInfo {
   typedef const void* (*GetInterfaceFunc)(const char*);
   typedef int (*PPP_InitializeModuleFunc)(PP_Module, PPB_GetInterface);
   typedef void (*PPP_ShutdownModuleFunc)();
 
@@ skipping 36 matching lines @@
   // entry points for the internal plugins.
   EntryPoints internal_entry_points;
 
   // Permission bits from ppapi::Permission.
   uint32_t permissions;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_COMMON_PEPPER_PLUGIN_INFO_H_