android_md5: base::StringPiece -> std::string_view

Bug: 691162
Change-Id: I460b7b275d3e5a9ed32e620d1a98f40dcf6bfbf4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5405581


Reviewed-by: Peter Wen <wnwen@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1281148}