Add instrumentation tests for face detection

Currently Android face detection has no tests.  This change rectifies
that situation.

These are instrumentation test rather than junit tests because face
detection doesn't actually return any results in junit.

The tests are registered to run as part of chrome_test_java.  These
are run on the linux_android_rel_ng trybots.

BUG=718329, 722931

Change-Id: I512aa4391f6910c7992781fb59cb9cd0bbd5fe58
Reviewed-on: https://chromium-review.googlesource.com/523013
Commit-Queue: Conley Owens <cco3@chromium.org>
Reviewed-by: Tommy Nyquist <nyquist@chromium.org>
Reviewed-by: Ken Rockot <rockot@chromium.org>
Reviewed-by: Miguel Casas <mcasas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#478078}

• chrome/android/BUILD.gn[diff]
• services/BUILD.gn[diff]
• services/shape_detection/android/javatests/src/org/chromium/shape_detection/FaceDetectionImplTest.java[Added - diff]
• services/shape_detection/face_detection_impl_mac_unittest.mm[diff]
• services/test/data/mona_lisa.jpg[Added - diff]