Move all custom slice uris to a registry class.

Change-Id: I192320f95ac81d14c8891ce2531d603912e59f56
Fixes: 119776308
Test: robotests

src/com/android/settings/notification/ZenModePreferenceController.java

@@ -35,6 +35,9 @@ import com.android.settingslib.core.lifecycle.events.OnResume;
 public class ZenModePreferenceController extends BasePreferenceController
         implements LifecycleObserver, OnResume, OnPause {
 
+
+    public static final String ZEN_MODE_KEY = "zen_mode";
+
     private SettingObserver mSettingObserver;
     private ZenModeSettings.SummaryBuilder mSummaryBuilder;