Add settings key for storing timeout to user 0 preference.

Bug: 213906356
Test: manual
Change-Id: Ic9c65e58a3f399753349dfcba20a1193a6f0eb00

core/java/android/provider/Settings.java

@@ -10047,6 +10047,13 @@ public final class Settings {
         @Readable
         public static final String QS_AUTO_ADDED_TILES = "qs_auto_tiles";
 
+        /**
+         * The duration of timeout, in milliseconds, to switch from a non-primary user to the
+         * primary user when the device is docked.
+         * @hide
+         */
+        public static final String TIMEOUT_TO_USER_ZERO = "timeout_to_user_zero";
+
         /**
          * Backup manager behavioral parameters.
          * This is encoded as a key=value list, separated by commas. Ex: