It raises the time to run the presubmit to ~30 seconds but it's still worth.

TEST=run more often

Review URL: http://codereview.chromium.org/3146010

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@55759 0039d316-1c4b-4281-b951-d872f2087c98