This provides compile testing of ANGLE's Ozone GBM back end.

BUG=762377

Change-Id: I3e6581307e303fe81fe754799cea9c09989e0d89
Reviewed-on: https://chromium-review.googlesource.com/660380Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Frank Henigman <fjhenigman@chromium.org>