[gnome-usage] memory-monitor: Use libgtop GTop.mem.user

[Gitlab System User <gitlab src gnome org>]

commit cf4b99d6bf792bca17619be61d7eab2b3b86a174
Author: Ben <bdejean gmail com>
Date:   Mon Oct 16 19:12:50 2017 +0000

    memory-monitor: Use libgtop GTop.mem.user
    
    That reflects how much RAM is used by users applications.
    
    Signed-off-by: Felipe Borges <felipeborges gnome org>

 src/memory-monitor.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/memory-monitor.vala b/src/memory-monitor.vala
index 9183c41..4327626 100644
--- a/src/memory-monitor.vala
+++ b/src/memory-monitor.vala
@@ -32,7 +32,7 @@ namespace Usage
             /* Memory */
             GTop.Mem mem;
             GTop.get_mem (out mem);
-            ram_usage = mem.used - mem.buffer - mem.cached;
+            ram_usage = mem.user;
             ram_total = mem.total;
 
             /* Swap */