Delete the user key when deleting a user.

BUG=19706593

Change-Id: I36ec1b987f5a07450c6a564c74f124ec8d3403ad
diff --git a/services/core/java/com/android/server/pm/UserManagerService.java b/services/core/java/com/android/server/pm/UserManagerService.java
index 15d1535a..d859442 100644
--- a/services/core/java/com/android/server/pm/UserManagerService.java
+++ b/services/core/java/com/android/server/pm/UserManagerService.java
@@ -42,6 +42,7 @@
 import android.os.ServiceManager;
 import android.os.UserHandle;
 import android.os.UserManager;
+import android.os.storage.StorageManager;
 import android.util.AtomicFile;
 import android.util.Log;
 import android.util.Slog;
@@ -1444,6 +1445,8 @@
     }
 
     private void removeUserStateLocked(final int userHandle) {
+        mContext.getSystemService(StorageManager.class)
+            .deleteUserKey(userHandle);
         // Cleanup package manager settings
         mPm.cleanUpUserLILPw(this, userHandle);