Fixes rounded corners for clear all button on low ram devices

Fixed rounded corners for clear all button by using a themed
background color on a shape with rounded corners instead of
programmatically changing the background color.

Change-Id: Iaaf4f0d94d417b0064c7e6bf4895b49d9fa6561f
Fixes: 67368134
Test: manual - go to recents and scroll up to show clear all button