- Create a new style for two action buttons.
- Change the layout of two_action_buttons.
Since we use same style for positive/nagative
buttons now, we only remain button1/button2 for
this layout.
- Create a setButtonIcon interface in ActionButtonPreference.
So, user can set icon for each button in this preferece.
Test: visual, robotest
Bug: 116346008
Change-Id: I511272cba5fd961349b85cae6d30004ddabe2c8e