CL: https://chromium-review.googlesource.com/c/535973/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c2db8578228a71611f79badf0d1b1d691528973e

commit c2db8578228a71611f79badf0d1b1d691528973e
Author: Evan Stade <estade@chromium.org>
Date: Mon Jun 26 22:55:52 2017

Make the Chrome OS battery image usable at various sizes. Reuse it
for tethers in the network list, which uses 20x20 images as opposed
to 16x16 as in the tray.

This also reduces the number of repeated constants and assumptions in
code concerning the size of the visible portion of the battery.

Bug: 672263,  733301 ,  736895 
Change-Id: Ia112ced4e70c7ea079cc5eea5dce1a9825647399
Reviewed-on: https://chromium-review.googlesource.com/535973
Commit-Queue: Terry Anderson <tdanderson@chromium.org>
Reviewed-by: Terry Anderson <tdanderson@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#482447}
[modify] https://crrev.com/c2db8578228a71611f79badf0d1b1d691528973e/ash/resources/vector_icons/BUILD.gn
[delete] https://crrev.com/d6c179267fc346b4a5809ec598e877e1515db419/ash/resources/vector_icons/system_tray_battery.1x.icon
[delete] https://crrev.com/d6c179267fc346b4a5809ec598e877e1515db419/ash/resources/vector_icons/system_tray_battery.icon
[modify] https://crrev.com/c2db8578228a71611f79badf0d1b1d691528973e/ash/system/network/network_list.cc
[modify] https://crrev.com/c2db8578228a71611f79badf0d1b1d691528973e/ash/system/power/power_status.cc
[modify] https://crrev.com/c2db8578228a71611f79badf0d1b1d691528973e/ash/system/power/power_status.h
[modify] https://crrev.com/c2db8578228a71611f79badf0d1b1d691528973e/ash/system/power/power_status_unittest.cc
[modify] https://crrev.com/c2db8578228a71611f79badf0d1b1d691528973e/ash/system/power/tray_power.cc