add bench for sprite-like drawing w/ imagefilters

visualbench run on Mac Pro

curr/maxrss	loops	min	median	mean	max	stddev	samples   	config	bench
  96/96  MB	16	412µs	413µs	413µs	414µs	0%	▄▁█▅▅▅▅▆▅▃▅	gpu	warmupbench
  98/98  MB	4	1.86ms	1.86ms	1.86ms	1.86ms	0%	▁▂▇█▆▅▇▄▃▃▃	gpu	image-filter-sprite-draw-image
 100/100 MB	4	1.86ms	1.86ms	1.86ms	1.86ms	0%	▆▇▅▄▁▆▅█▅▄▅	gpu	image-filter-sprite-draw-bitmap
 100/100 MB	32	547µs	548µs	590µs	1.01ms	24%	█▁▁▁▁▁▁▁▁▁▁	gpu	image-filter-sprite-draw-sprite

BUG=skia:

Review URL: https://codereview.chromium.org/1497843003
1 file changed