Convert enable_plugins to a buildflag header.

chrome/browser/renderer_context_menu/render_view_context_menu.cc

Index: chrome/browser/renderer_context_menu/render_view_context_menu.cc
diff --git a/chrome/browser/renderer_context_menu/render_view_context_menu.cc b/chrome/browser/renderer_context_menu/render_view_context_menu.cc
index 3762746fd341d79e90b241a36b5a1411686a6f38..7340f255ec4408122768752487deae9817a226b1 100644
--- a/chrome/browser/renderer_context_menu/render_view_context_menu.cc
+++ b/chrome/browser/renderer_context_menu/render_view_context_menu.cc
@@ -107,6 +107,7 @@
 #include "content/public/common/url_utils.h"
 #include "extensions/features/features.h"
 #include "net/base/escape.h"
+#include "ppapi/features/features.h"
 #include "printing/features/features.h"
 #include "third_party/WebKit/public/public_features.h"
 #include "third_party/WebKit/public/web/WebContextMenuData.h"
@@ -910,7 +911,7 @@ bool RenderViewContextMenu::IsHTML5Fullscreen() const {
   return controller->IsTabFullscreen();
 }
 
-#if defined(ENABLE_PLUGINS)
+#if BUILDFLAG(ENABLE_PLUGINS)
 void RenderViewContextMenu::HandleAuthorizeAllPlugins() {
   ChromePluginServiceFilter::GetInstance()->AuthorizeAllPlugins(
       source_web_contents_, false, std::string());