CRAS: Add ResendBatteryLevel method

Add a new DBus method ResendBatteryLevel It will be used to support
showing battery level for BT headsets.

This is to cover cases that Chrome cleaned the saved battery level and
need to query the value again.

BUG=b:166530001
TEST=dbus-monitor --system "sender='org.chromium.cras', \
member=BluetoothBatteryChanged"
dbus-send --system --print-reply --dest=org.chromium.cras \
/org/chromium/cras org .chromium.cras.Control.ResendBluetoothBattery

Change-Id: Iedb4afe0cf23c71fd30b9c74ea33322f0d3cf554
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/adhd/+/2396355
Reviewed-by: Alain Michaud <alainm@chromium.org>
Tested-by: En-Shuo Hsu <enshuo@chromium.org>
Commit-Queue: Alain Michaud <alainm@chromium.org>
5 files changed