Stop showing software keyboard when appropriate

This change assumes the structure inside layout file.
We will change the structure inside the layout, so
fundemental fix should come along the layout change.

Also let software keyboard hide when appropriate.
onBackButtonPressed() loses the focus and hiding
the keyboard doesn't work fine after the call.

Bug: 3192886
Change-Id: Ifd28d1f1fd0d6f72dc1c32c066dd793c6f9f36ab