Convert enable_plugins to a buildflag header.

components/renderer_context_menu/render_view_context_menu_base.h

Index: components/renderer_context_menu/render_view_context_menu_base.h
diff --git a/components/renderer_context_menu/render_view_context_menu_base.h b/components/renderer_context_menu/render_view_context_menu_base.h
index 5ea257c99760d1e2394468181b8142d74f13f272..028d4ff038e092ca02b6be6494a2c70628d1b43c 100644
--- a/components/renderer_context_menu/render_view_context_menu_base.h
+++ b/components/renderer_context_menu/render_view_context_menu_base.h
@@ -20,6 +20,7 @@
 #include "components/renderer_context_menu/render_view_context_menu_observer.h"
 #include "components/renderer_context_menu/render_view_context_menu_proxy.h"
 #include "content/public/common/context_menu_params.h"
+#include "ppapi/features/features.h"
 #include "ui/base/models/simple_menu_model.h"
 #include "ui/base/page_transition_types.h"
 #include "ui/base/window_open_disposition.h"
@@ -144,7 +145,7 @@ class RenderViewContextMenuBase : public ui::SimpleMenuModel::Delegate,
   // Increments histogram value for visible context menu item specified by |id|.
   virtual void RecordShownItem(int id) = 0;
 
-#if defined(ENABLE_PLUGINS)
+#if BUILDFLAG(ENABLE_PLUGINS)
   virtual void HandleAuthorizeAllPlugins() = 0;
 #endif