system_api: Add SetBacklightBrightnessRequest powerd proto.

Add a SetBacklightBrightnessRequest protocol message that
Chrome will send to powerd via SetScreenBrightnessPercent
D-Bus method calls. These calls currently send raw D-Bus
arguments, but a new "cause" argument is needed.

Also add a new "MODEL" enum value to
BacklightBrightnessChange's "cause" enum.

TEST=built it

Change-Id: Ife2fc6741ece56620ced37feab8e33c093aeae0a
Commit-Ready: Dan Erat <>
Tested-by: Dan Erat <>
Reviewed-by: Jia Meng <>
Reviewed-by: Dan Erat <>
1 file changed