Add presubmit check for #pragma once.

BUG=none
TEST=git cl presubmit

Review URL: https://chromiumcodereview.appspot.com/10704150

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@146166 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed