For now, slice view shows screen title by default, but it isn't approprate for some simple cases. ie, device model, phone number, android version etc. So, We create a new attribue which let BasePreferenceController be more flxible. User can choose what they want to show in summary text. Fixes: 74900516 Test: make RunSettingsRoboTests Change-Id: I2788c6edfaf8e656170a507607f22513841a3e0a