Convert enable_plugins to a buildflag header.

content/common/frame_messages.h

Index: content/common/frame_messages.h
diff --git a/content/common/frame_messages.h b/content/common/frame_messages.h
index b2faebf791fe3579d15507149c6b1978d1ee76a0..de03e5577869d83b837a828f4cc9c49caff7014e 100644
--- a/content/common/frame_messages.h
+++ b/content/common/frame_messages.h
@@ -42,6 +42,7 @@
 #include "content/public/common/transition_element.h"
 #include "ipc/ipc_message_macros.h"
 #include "ipc/ipc_platform_file.h"
+#include "ppapi/features/features.h"
 #include "third_party/WebKit/public/platform/WebFocusType.h"
 #include "third_party/WebKit/public/platform/WebInsecureRequestPolicy.h"
 #include "third_party/WebKit/public/web/WebFindOptions.h"
@@ -56,7 +57,7 @@
 #include "url/gurl.h"
 #include "url/origin.h"
 
-#if defined(ENABLE_PLUGINS)
+#if BUILDFLAG(ENABLE_PLUGINS)
 #include "content/common/pepper_renderer_instance_data.h"
 #endif
 
@@ -575,7 +576,7 @@ IPC_STRUCT_BEGIN(FrameHostMsg_ShowPopup_Params)
 IPC_STRUCT_END()
 #endif
 
-#if defined(ENABLE_PLUGINS)
+#if BUILDFLAG(ENABLE_PLUGINS)
 IPC_STRUCT_TRAITS_BEGIN(content::PepperRendererInstanceData)
   IPC_STRUCT_TRAITS_MEMBER(render_process_id)
   IPC_STRUCT_TRAITS_MEMBER(render_frame_id)
@@ -908,7 +909,7 @@ IPC_MESSAGE_ROUTED2(FrameMsg_SaveImageAt,
                     int /* x */,
                     int /* y */)
 
-#if defined(ENABLE_PLUGINS)
+#if BUILDFLAG(ENABLE_PLUGINS)
 // Notifies the renderer of updates to the Plugin Power Saver origin whitelist.
 IPC_MESSAGE_ROUTED1(FrameMsg_UpdatePluginContentOriginWhitelist,
                     std::set<url::Origin> /* origin_whitelist */)
@@ -918,7 +919,7 @@ IPC_MESSAGE_ROUTED1(FrameMsg_UpdatePluginContentOriginWhitelist,
 IPC_MESSAGE_ROUTED2(FrameMsg_SetPepperVolume,
                     int32_t /* pp_instance */,
                     double /* volume */)
-#endif  // defined(ENABLE_PLUGINS)
+#endif  // BUILDFLAG(ENABLE_PLUGINS)
 
 // Used to instruct the RenderFrame to go into "view source" mode. This should
 // only be sent to the main frame.
@@ -1129,7 +1130,7 @@ IPC_SYNC_MESSAGE_CONTROL3_1(FrameHostMsg_Are3DAPIsBlocked,
                             content::ThreeDAPIType /* requester */,
                             bool /* blocked */)
 
-#if defined(ENABLE_PLUGINS)
+#if BUILDFLAG(ENABLE_PLUGINS)
 // Notification sent from a renderer to the browser that a Pepper plugin
 // instance is created in the DOM.
 IPC_MESSAGE_ROUTED1(FrameHostMsg_PepperInstanceCreated,
@@ -1265,7 +1266,7 @@ IPC_MESSAGE_CONTROL3(FrameHostMsg_PluginInstanceThrottleStateChange,
                      int /* plugin_child_id */,
                      int32_t /* pp_instance */,
                      bool /* is_throttled */)
-#endif  // defined(ENABLE_PLUGINS)
+#endif  // BUILDFLAG(ENABLE_PLUGINS)
 
 // Satisfies a Surface destruction dependency associated with |sequence|.
 IPC_MESSAGE_ROUTED1(FrameHostMsg_SatisfySequence,