Since SysUI holds these bitmaps in memory for jank-free
drawing, these pixels are just wasted RAM. Since the
transition code assumes uniform square bitmaps, these are
all 64x64dp, which is still a teensy bit wasteful but much
better than before (144x144dp).

Bug: 18369196
Change-Id: Idf10b2048190ac44eff3e5da467149c460067347