ash: Add vertical spacing to multi-line text in tray.

ash/system/tray/tray_constants.cc

Index: ash/system/tray/tray_constants.cc
diff --git a/ash/system/tray/tray_constants.cc b/ash/system/tray/tray_constants.cc
index 6c182fd0ea04884026db723a33de0981c26ae53f..de787f9ec9a958248c399bf01f423ce4709b2493 100644
--- a/ash/system/tray/tray_constants.cc
+++ b/ash/system/tray/tray_constants.cc
@@ -12,6 +12,7 @@ const int kTrayPopupAutoCloseDelayInSeconds = 2;
 const int kTrayPopupAutoCloseDelayForTextInSeconds = 5;
 const int kTrayPopupPaddingHorizontal = 18;
 const int kTrayPopupPaddingBetweenItems = 10;
+const int kTrayPopupTextSpacingVertical = 4;
 
 const int kTrayPopupItemHeight = 48;
 const int kTrayPopupDetailsIconWidth = 27;