The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/522b207a08ea3e2414c64a70a92fc8760c619b57

commit 522b207a08ea3e2414c64a70a92fc8760c619b57
Author: Tetsui Ohkubo <tetsui@chromium.org>
Date: Wed Aug 29 16:38:40 2018

Unified: Fix horizontal padding for Tray button

Clock has 3dip padding on the left and the right. Old System Tray had
3dip padding on the right, because clock was on the left. In Unified,
clock is on the right, so we should swap the horizontal padding.

TEST=manual
BUG= 860796 

Change-Id: I6b21f8cc27228f83500adc4062564a83211fbdcc
Reviewed-on: https://chromium-review.googlesource.com/1192565
Reviewed-by: James Cook <jamescook@chromium.org>
Commit-Queue: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#587152}
[modify] https://crrev.com/522b207a08ea3e2414c64a70a92fc8760c619b57/ash/system/status_area_widget_delegate.cc