viz: Use base::size instead of arraysize

arraysize is deprecated and base::size should be used instead.
This CL changes arraysize to base::size in SurfaceAggragator
unittests

Bug: 837308
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: I747970ac6bbecfe4bb9634b6ed37d3cbcb09f6b4
Reviewed-on: https://chromium-review.googlesource.com/1080248
Reviewed-by: danakj <danakj@chromium.org>
Commit-Queue: Daniele Castagna <dcastagna@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563256}
1 file changed