question: public void userForeground ( int userId ) { synchronized ( mPackagesLock ) { VUserInfo user = mUsers . get ( userId ) ; long now = System . currentTimeMillis ( ) ; if ( user == null || user . partial ) { VLog . w ( LOG_TAG , "userForeground: unknown user #" + userId ) ; return ; } if ( now > EPOCH_PLUS_30_YEARS ) { user . lastLoggedInTime = now ; writeUserLocked ( user ) ; } } }
target:  Make a note of the last started time of a user.