Unhappy [Q] [HOWTO] Use volume button to wake up my phone on CM11

The rom is cm-11-20140804-SNAPSHOT-M9-maserati.zip

In the android 4.4.2, I can modify the android.policy.jar file to allow me wake up my phone using volume button. Or in old CM system, there has a option allows me to wake up my phone using volume button.
But in this version of CM11, they removed this option, so how can I wake up my phone using volume button.

I have tried modify the /data/data/com.android.providers.settings/databases/settings.db but it works only for the first 5 mins since screen goes off.
I tried to locate the file \smali\com\android\internal\policy\impl\KeyguardVi ewMediator.smali in android.policy.jar, but it has gone.