Fix missing observer reply callbacks

This was causing upto 2 seconds in user switching delay.

Also switched to using Log.wtf for the timeout message to
track any regressions in this due to new clients.

Bug: 25813588
Change-Id: Icf23b021f134a8ccfa2dae470af02b2da7454acc
diff --git a/services/core/java/com/android/server/am/UserController.java b/services/core/java/com/android/server/am/UserController.java
index 6d8bd1c..4b2a55f 100644
--- a/services/core/java/com/android/server/am/UserController.java
+++ b/services/core/java/com/android/server/am/UserController.java
@@ -674,7 +674,7 @@
 
     void timeoutUserSwitch(UserState uss, int oldUserId, int newUserId) {
         synchronized (mService) {
-            Slog.w(TAG, "User switch timeout: from " + oldUserId + " to " + newUserId);
+            Slog.wtf(TAG, "User switch timeout: from " + oldUserId + " to " + newUserId);
             sendContinueUserSwitchLocked(uss, oldUserId, newUserId);
         }
     }