[Chrome OS MD] Draw a 1px separator between 2 tray items

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 39b206075b8f8a254966e0b929b90e0544f33923..986b1f94cf4f310cc8f26cec658d66dfbfa0ab4c 100644
--- a/ash/common/system/tray/tray_constants.h
+++ b/ash/common/system/tray/tray_constants.h
@@ -76,6 +76,13 @@ extern const int kTrayNotificationContentsWidth;
 
 extern const int kMessageCenterBubblePadding;
 
+// Extra padding used to adjust hitting region around tray items.
+extern const int kHitRegionPadding;
+
+// Color and width of a line used to separate tray items in the shelf.
+extern const SkColor kSeparatorColor;
+extern const int kSeparatorWidth;
+
 // The size and foreground color of the icons appearing in the material design
 // system tray.
 extern const int kTrayIconSize;