Add devkit-power to chrome://system BUG=chromium-os:9006 TEST=Opened chrome://system. Checked that devkit-power output is consistent with running from console. Change-Id: I5140ee26b02a9398efd31dfd5666a1c3cad33121 Signed-off-by: Benson Leung <[email protected]> Signed-off-by: Sameer Nanda <[email protected]> Review URL: http://codereview.chromium.org/5063001