GitLab

- DCHECK(false) -> NOTREACHED()
- Extract date conversion to a helper function

BUG=none
TEST=none

Review URL: https://chromiumcodereview.appspot.com/10375055

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@137739 0039d316-1c4b-4281-b951-d872f2087c98