sdk: Fix UserContentObserver build

Change-Id: Ic0f38473b3d1f1a59deafc7810ecffd37d9ba0fc
diff --git a/src/org/omnirom/omnilib/internal/common/UserContentObserver.java b/src/org/omnirom/omnilib/internal/common/UserContentObserver.java
index 916bc4b..000d2ff 100644
--- a/src/org/omnirom/omnilib/internal/common/UserContentObserver.java
+++ b/src/org/omnirom/omnilib/internal/common/UserContentObserver.java
@@ -23,7 +23,8 @@
 
     private IUserSwitchObserver mUserSwitchObserver = new IUserSwitchObserver.Stub() {
         @Override
-        public void onBeforeUserSwitching(int newUserId) throws RemoteException {
+        public void onBeforeUserSwitching(int newUserId, IRemoteCallback reply)
+                throws RemoteException {
         }
         @Override
         public void onUserSwitching(int newUserId, IRemoteCallback reply) {