Merge \"Prevent NPE in dispatchUserSwitch\" into nyc-mr1-dev

                try {

                    // Prepend with unique prefix to guarantee that keys are unique

                    final String name = "#" + i + " " + mUserSwitchObservers.getBroadcastCookie(i);

                    mCurWaitingUserSwitchCallbacks.add(name);

                    synchronized (mService) {

                        curWaitingUserSwitchCallbacks.add(name);

                    }

                    final IRemoteCallback callback = new IRemoteCallback.Stub() {

                        @Override

                        public void sendResult(Bundle data) throws RemoteException {