Battery listener for download service in native code.
We need to listen to battery change when Chrome is running.
This class decouples the battery listening details from download
service. Any underlying implementation change can be limited inside
this class.
In the future we may use device service to retrieve battery level,
right now it seems only content can embbed the device service.
BUG=717180
Review-Url: https://codereview.chromium.org/2867073004
Cr-Commit-Position: refs/heads/master@{#470676}
4 files changed
