[ash-md] Changed the system info row height to 40 (instead of 48).

ash/common/system/tray/tray_constants.h

Index: ash/common/system/tray/tray_constants.h
diff --git a/ash/common/system/tray/tray_constants.h b/ash/common/system/tray/tray_constants.h
index 7219d2a8aa3031121501249b2dddd29a9dc2bbd5..aa187250d6a889394da90ec8dcbc9450265cec82 100644
--- a/ash/common/system/tray/tray_constants.h
+++ b/ash/common/system/tray/tray_constants.h
@@ -140,6 +140,9 @@ extern const int kTrayPopupInkDropInset;
 // The radius used to draw the corners of the rounded rect style ink drops.
 extern const int kTrayPopupInkDropCornerRadius;
 
+// The height of the system info row.
+extern const int kTrayPopupSystemInfoRowHeight;
+
 enum TrayConstant {
   // A legacy height value used in non-MD calculations for applying additional
   // borders on tray items.