Add some missing ENABLE_PLUGINS ifdefs.

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 1d9be84746a0118baef26b39d2f79dd6ea2d271e..6460831b32d393c1039a85e3f7409cda2025035b 100644
--- a/content/common/frame_messages.h
+++ b/content/common/frame_messages.h
@@ -600,6 +600,7 @@ IPC_MESSAGE_ROUTED2(FrameHostMsg_DomOperationResponse,
                     std::string  /* json_string */,
                     int  /* automation_id */)
 
+#if defined(ENABLE_PLUGINS)
 // Sent to the browser when the renderer detects it is blocked on a pepper
 // plugin message for too long. This is also sent when it becomes unhung
 // (according to the value of is_hung). The browser can give the user the
@@ -630,6 +631,7 @@ IPC_SYNC_MESSAGE_CONTROL4_3(FrameHostMsg_GetPluginInfo,
                             bool /* found */,
                             content::WebPluginInfo /* plugin info */,
                             std::string /* actual_mime_type */)
+#endif  // defined(ENABLE_PLUGINS)
 
 // A renderer sends this to the browser process when it wants to
 // create a plugin.  The browser will create the plugin process if