Allow users of the git recipe module to specify infra_step
Allow users of the git recipe module to specify infra_step

BUG=493885

Review URL: https://codereview.chromium.org/1178263003.

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@295708 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build