This change also syncs the drawables with Master.
Cherry-pick: I2573786aac5fd8d543cf12d24c951b67c7353fd7
Bug: 4436327
Change-Id: I88dc0162033a1017040205590c0c34a5111b835a
Cherrypick I44f3b2eef8086d6e0b0db53d38f08487549060c6 from Gingerbread
This change also introduces the key background drawables which has no
fixed bottom padding. Instead of relying on bottom padding in
drawable, this change also specifies Keyboard.verticalGap with
physical unit. Other keyboard related length, distance and size are
also specified by physical unit.
Bug: 3066107
Change-Id: Ib38355ebfc2f8d5b1d26c4e90eba87196fbeddfa