b/6232528 Reduce volume persist delay to 500ms

Change-Id: I45c32da0a1089ce8bc865e12b51c069a6db28fd4
diff --git a/media/java/android/media/AudioService.java b/media/java/android/media/AudioService.java
index 985cdf4..521bb15 100644
--- a/media/java/android/media/AudioService.java
+++ b/media/java/android/media/AudioService.java
@@ -92,7 +92,7 @@
     protected static final boolean DEBUG_RC = false;
 
     /** How long to delay before persisting a change in volume/ringer mode. */
-    private static final int PERSIST_DELAY = 3000;
+    private static final int PERSIST_DELAY = 500;
 
     private Context mContext;
     private ContentResolver mContentResolver;