Change chrome tests to run on qemu image, not test image.
Change chrome tests to run on qemu image, not test image.

While the test image can run in a VM, it has no stateful partition and thus
all chrome tests abort quickly.

BUG=chromium-os:21462
TEST=Unittests

Change-Id: I945543bec133f3844f05a90a50579414459156f0
Reviewed-on: http://gerrit.chromium.org/gerrit/9802
Reviewed-by: Chris Sosa <959d3d631fb6f17f1b07f751372041a1edb210d1@chromium.org>
Tested-by: Chris Sosa <959d3d631fb6f17f1b07f751372041a1edb210d1@chromium.org>

coreos/chromite,zhang0137/chromite,zhang0137/chromite,chadversary/chromiumos.chromite,coreos/chromite,coreos/chromite,bpsinc-native/src_third_party_chromite,chadversary/chromiumos.chromite,bpsinc-native/src_third_party_chromite,bpsinc-native/src_third_party_chromite,zhang0137/chromite