Add left/right layout support for uber 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 10756c6f92beb53b01148826d8f57c59a997a801..11a9d88a4fd677744f3ef83cdd2215384a7020be 100644
--- a/ash/system/tray/tray_constants.cc
+++ b/ash/system/tray/tray_constants.cc
@@ -8,8 +8,11 @@
 
 namespace ash {
 
-const int kPaddingFromRightEdgeOfScreen = 15;
-const int kPaddingFromBottomOfScreen = 10;
+const int kPaddingFromRightEdgeOfScreenBottomAlignment = 15;
+const int kPaddingFromBottomOfScreenBottomAlignment = 10;
+const int kPaddingFromLeftEdgeOfScreenLeftAlignment = 13;
+const int kPaddingFromRightEdgeOfScreenRightAlignment = 2;
+const int kPaddingFromBottomOfScreenVerticalAlignment = 9;
 
 const int kTrayPopupAutoCloseDelayInSeconds = 2;
 const int kTrayPopupAutoCloseDelayForTextInSeconds = 5;