Implement better handling of back press when keyboard is showing on search bar

[sblatz]

Per recommendation here, it'd be great if our "hide keyboard" button also called onBackPressed.

It seems like we can achieve this by listening to KeyEvent.BACK

┆Issue is synchronized with this Jira Task

[sblatz]

I'm happy to work on this, but want the a-c team's input on whether or not they think this is a good idea :)

[pocmo]

Yes, I think that is a great idea. I thought that may not really be possible since the keyboard is handling the back button key. But since Chrome can do it .. there's a way. :)

onKeyPreIme from the linked Stackoverflow posting looks good. :)

[Cheap-Skate]

Thanks!