Add a layout type named "big" to allow for gmerge/chrome development
Add a layout type named "big" to allow for gmerge/chrome development

BUG=none
TEST=build_image --board=stumpy --disk_layout=big

Change-Id: Id48bbdda2b3a570e267ae860acb87415db82a9b9
Reviewed-on: https://gerrit.chromium.org/gerrit/34685
Reviewed-by: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>
Commit-Ready: Liam McLoughlin <a63c1d66dbd75d3cc434e11bdf376be6f9ff043b@chromium.org>
Tested-by: Liam McLoughlin <a63c1d66dbd75d3cc434e11bdf376be6f9ff043b@chromium.org>
Reviewed-by: Peter Mayo <3d31fdaf44dc55bb1b4f50b19df9bc879177d37a@chromium.org>

mjg59/scripts,vmware/coreos-scripts,marineam/coreos-scripts,mjg59/scripts,andrejro/coreos--scripts,trnubo/scripts,crawford/scripts,mischief/scripts,endocode/scripts,crawford/scripts,bcwaldon/coreos-scripts,zhang0137/scripts,vmware/coreos-scripts,nicescale/scripts,coreos/scripts,fivethreeo/scripts,mischief/scripts,mischief/scripts,smilart/scripts,trnubo/scripts,smilart/scripts,vmware/coreos-scripts,andrejro/coreos--scripts,gtank/scripts,BugRoger/scripts,endocode/scripts,crawford/scripts,glevand/coreos--scripts,mjg59/scripts,glevand/coreos--scripts,fivethreeo/scripts,BugRoger/scripts,bcwaldon/coreos-scripts,gtank/scripts,zhang0137/scripts,marineam/coreos-scripts,sigma/coreos-scripts,gtank/scripts,nicescale/scripts,trnubo/scripts,andrejro/coreos--scripts,endocode/scripts,fivethreeo/scripts,nicescale/scripts,bcwaldon/coreos-scripts,sigma/coreos-scripts,sigma/coreos-scripts,marineam/coreos-scripts,zhang0137/scripts,coreos/scripts,BugRoger/scripts,smilart/scripts