ShapeDetection: Move VisionAPIAsyncRequestMac to a common location

Only move code without modifying the implementation so that Barcode Detection
can reuse it.

BUG=848182

Cq-Include-Trybots: luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win10_chromium_x64_rel_ng
Change-Id: Ia04a56efbd2ace4eb05f0ebaa4e341ef7a032fa4
Reviewed-on: https://chromium-review.googlesource.com/1128625
Commit-Queue: Junwei Fu <junwei.fu@intel.com>
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Reviewed-by: Miguel Casas <mcasas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575522}
4 files changed