question: @ VisibleForTesting EnumSet < FailureReason > failureReasons ( Context context ) { EnumSet < FailureReason > reasons = EnumSet . noneOf ( FailureReason . class ) ; reasons . addAll ( mPrecacheLauncher . failureReasons ( ) ) ; if ( ! mDeviceState . isPowerConnected ( context ) ) reasons . add ( FailureReason . NO_POWER ) ; if ( ! mDeviceState . isWifiAvailable ( context ) ) reasons . add ( FailureReason . NO_WIFI ) ; if ( timeSinceLastPrecacheMs ( context ) < WAIT_UNTIL_NEXT_PRECACHE_MS ) { reasons . add ( FailureReason . NOT_ENOUGH_TIME_SINCE_LAST_PRECACHE ) ; } if ( PrecacheService . isPrecaching ( ) ) reasons . add ( FailureReason . CURRENTLY_PRECACHING ) ; return reasons ; }
target:  Returns the set of reasons that the last prefetch attempt failed to start.