cpu: base::StringPiece -> std::string_view

Bug: 691162
Change-Id: I9d35d11ad8dd07aaac8582afc190f73a7a4961d2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5407334


Reviewed-by: Francois Pierre Doray <fdoray@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1281234}