Convert enable_plugins to a buildflag header.

chrome/common/chrome_switches.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.
 
 // Defines the shared command-line switches used by code in the Chrome
 // directory that don't have anywhere more specific to go.
 
 #ifndef CHROME_COMMON_CHROME_SWITCHES_H_
 #define CHROME_COMMON_CHROME_SWITCHES_H_
 
 #include "build/build_config.h"
+#include "ppapi/features/features.h"
 #include "printing/features/features.h"
 
 // Don't add more switch files here. This is linked into some places like the
 // installer where dependencies should be limited. Instead, have files
 // directly include your switch file.
 
 namespace base {
 class CommandLine;
 };
 
@@ skipping 346 matching lines @@
 extern const char kViewerLaunchViaAppId[];
 extern const char kWatcherProcess[];
 extern const char kWindows10CustomTitlebar[];
 extern const char kWindows8Search[];
 #endif  // defined(OS_WIN)
 
 #if BUILDFLAG(ENABLE_PRINT_PREVIEW) && !defined(OFFICIAL_BUILD)
 extern const char kDebugPrint[];
 #endif
 
-#if defined(ENABLE_PLUGINS)
+#if BUILDFLAG(ENABLE_PLUGINS)
 extern const char kAllowNaClCrxFsAPI[];
 extern const char kAllowNaClFileHandleAPI[];
 extern const char kAllowNaClSocketAPI[];
 #endif
 
 #if defined(ENABLE_WAYLAND_SERVER)
 extern const char kEnableWaylandServer[];
 #endif
 
 #if defined(OS_WIN) || defined(OS_LINUX)
@@ skipping 14 matching lines @@
 #if defined(OS_WIN)
 bool GDITextPrintingEnabled();
 #endif
 
 // DON'T ADD RANDOM STUFF HERE. Put it in the main section above in
 // alphabetical order, or in one of the ifdefs (also in order in each section).
 
 }  // namespace switches
 
 #endif  // CHROME_COMMON_CHROME_SWITCHES_H_