Device default value set in config_keyChordPowerVolumeUp in
config.xml; can be overridden for all users with
Settings.Global.KEY_CHORD_POWER_VOLUME_UP.
Value may be one of:
0 - no-op
1 - vibrate mode (current AOSP default behavior)
2 - launch assistant
Bug: 179673796
Test: adb shell settings put global key_chord_volume_up <0, 1, or 2>
adb shell dumpsys window | grep mPowerVolUpBehavior
adb shell input keycombination POWER VOLUME_UP
Change-Id: I0e03155bdbe61d9fdd6838fe2c860749cf360907
069278cdb7