Disable patch_grid benches on the Xoom, which crash in GPU mode.
Disable patch_grid benches on the Xoom, which crash in GPU mode.

BUG=skia:2847
R=caryclark@google.com, mtklein@google.com, bsalomon@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/481683004

google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot