Our previous change to use static_assert leads the new wave of c++11
features.

BUG=

Change-Id: Id6d382475daa7029109dab1017a59b5ef07c18df
Reviewed-on: https://chromium-review.googlesource.com/221267Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>