[Battery Monitor] Use "Has Cumulative" instead of total battery count for tray icon

This fixes the battery icon errorneously showing an empty red battery on a desktop
computer with a wireless mouse/keyboard; instead the "no battery" icon with a
red cross is shown.

CHANGELOG: Battery icon no longer errorneously reports an empty battery if computer has none

CCBUG: 362924
Reviewed-By: mgraesslin