- Link-up between the preview, font size, and display size preferences. - Add the preview preference and entry. Bug: 211503117 Test: make RunSettingsRoboTests ROBOTEST_FILTER=TextReadingPreviewControllerTest Test: make RunSettingsRoboTests ROBOTEST_FILTER=TextReadingPreviewPreferenceTest Change-Id: Ic6c48861a0051670fd78b13dca5488711de30cb8