Add nightly build method to helper class to easily generate nightly schedulers.
Add nightly build method to helper class to easily generate nightly schedulers.

BUG=chromium-os:36919
TEST=Used it in chromeos.chrome with hour=[0]. Saw it work as expected.


Review URL: https://chromiumcodereview.appspot.com/11428156

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@171078 0039d316-1c4b-4281-b951-d872f2087c98

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