(It's not clear to me why only some projects/compilers are complaining
but other parts of the code are using the explicit namespace.)
Change-Id: I24b0c3b8104932b4ec82a25f5eb96c08abff87b5
Reviewed-on: https://dawn-review.googlesource.com/c/2901
Reviewed-by: Kai Ninomiya <kainino@chromium.org>