HandlerScheduler.scheduleDirect supports async option?

[satoshun]

RxAndroid support async option v2.1.0. now, it support only in HandlerWorker.schedule.

I think, HandlerScheduler.scheduleDirect should be support async option.
Because, some RxJava operator use Scheduler.scheduleDirect method (ex, Maybe.observeOn)

(i prepared source code in 2.x...satoshun:2.x)

[ZacSweers]

Hmm, that's a good shout. It'd be nicer if we could just use the hidden constructor of Handler to enable this at the handler level, but that implementation looks fine too. Looks like this affects all the observe/subscribe/dispose-"on" operators as well

@JakeWharton @adamp thoughts?

[JakeWharton]

I'd rather do the simple thing. I was hoping the recent release would be the last. Maybe this one will stick...

[adamp]

Consistency looks good to me.

[satoshun]

thx reply!

Handler level async can use from API28 via Handler#createAsync. It makes the code more complicated.

I think that it is unnatural not to consider async option in HandlerScheduler.scheduleDirect.

I opened PR, If there is no problem please review it.