Because the holo theme drawables have "holo" effect around 9-patch as
fixed size image, so we need dedicated drawables for each sw600dp-mdpi
and sw768dp-mdpi resolutions for visual designers.
* drawable-mdpi (fallback resources)
* drawable-sw600dp-mdpi (7" tablet, phone style keyboard, placeholder for now)
* drawable-sw768dp-mdpi (10" tablet, tablet style keybaord)
Note that:
* Eventually sw600dp drawables will be updated by designers.
* We need sw768dp drawable copies because, without these, 10" tablet
will use updated sw600dp drawables wrongly.
* We have to keep drawable-mdpi as final fallback resources.
Bug: 4436327
Change-Id: I93db87ee99c2abb8d18e869e5411e3cb5bec1020