Avoid clashing two IsUsingMus() functions in jumbo builds

In some jumbo configurations the two IsUsingMus would end up
in the same compilation unit and cause compilation errors.
The function is small enough (barely) to have in two copies so
this patch moves them to a tighter namespace.

Bug: 746953
Change-Id: I08b67606fd6dc68ee5ae9a8c91c79386051f8976
Reviewed-on: https://chromium-review.googlesource.com/749386
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Daniel Bratell <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#513732}
4 files changed