rename heads up global setting: base part

Bug: 13208692
Change-Id: Ia020e4d63552ab4b8cbb8a37622c36776800a790
diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index 0f68f2b..bf0be40 100644
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -6112,7 +6112,8 @@
          *
          * @hide
          */
-        public static final String HEADS_UP = "heads_up_enabled";
+        public static final String HEADS_UP_NOTIFICATIONS_ENABLED =
+                "heads_up_notifications_enabled";
 
         /** @hide */ public static final int HEADS_UP_OFF = 0;
         /** @hide */ public static final int HEADS_UP_ON = 1;