Nit: even better, apply the standard format of this header, per [Mozilla License Headers](http://www.mozilla.org/MPL/headers/), which will make it easier to update it automatically (in case we ever have to do that again):

```
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
```