Settings: fix an issue where text is not showing up on first instance.

* Even though we set setOnSeekBarChangeListener which should
setProgress notify the onProgressChanged method.

* When the slider set at 0, it does not invoke a onProgressChanged
because the value was set at 0, this causes the update method in
observer patttern to be ignored.

Change-Id: I0306504d2a32122636e78858e501c90a3e7797dc